MVR (mechanical vapor recompression)-based boiler secondary flash steam waste heat recovery system and method

Abstract

The invention discloses a boiling pot secondary flash steam waste heat recovery system and method based on MVR, and the system comprises a boiling pot, a steam-liquid separator, a steam compressor, a steam reutilization device, a flash tank and an ejector, the steam reutilization device is arranged in the boiling pot, and the flash tank is arranged in the boiling pot; a steam outlet of the boiling pot is sequentially connected with an inlet adjusting valve, a steam-liquid separator and a steam compressor through pipelines, an outlet adjusting valve is finally connected to a steam recycling device to form a first steam loop, and the output end of the steam recycling device is communicated with the flash tank and the ejector through pipelines in sequence and then is communicated with the steam compressor. Original waste secondary flash steam is completely recycled, the quality of the steam is improved, then the steam is reused, a large amount of live steam needed by a boiling pot is directly replaced, the energy-saving rate is increased, and meanwhile consumption of cooling water and heat pollution are greatly reduced. The boiling pot secondary flash steam waste heat recovery system and method based on the MVR have the effect of being remarkable in energy saving effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial boiling equipment, and in particular to a boiling kettle secondary flash steam waste heat recovery system and method based on MVR. BACKGROUND

[0002] In the beer industry, boiling kettle is a widely used key equipment. Its malt boiling process usually includes wort preheating, wort boiling, wort precooling, and the secondary steam of wort boiling flash is currently directly discharged or used to heat intermediate thermal energy water using a heat exchanger, and then the intermediate thermal energy water is used to preheat the cold wort, but a large amount of steam is still consumed for boiling. Nowadays, using MVR technology can produce high-grade low-pressure steam for boiling kettle to heat wort by consuming a small amount of electricity from low-grade secondary flash steam, and the wort boiling discharge condensate water is fully utilized for wort preheating.

[0003] Steam recompression technology is a high-efficiency waste heat recovery technology, and its core principle is to work on low-grade steam through a steam compressor to improve its pressure, temperature and enthalpy, so that it becomes high-grade steam that can meet the process requirements and is sent back to the system as a heat source, thereby greatly reducing the consumption of primary energy.

[0004] The present application proposes an MVR waste heat recovery system that can adapt to changes in working conditions, intelligently control, and be efficient and stable, to fully utilize steam heat and achieve the effect of reducing energy consumption.

[0005] However, there are challenges in directly applying MVR technology to secondary steam recovery of boiling kettle:

[0006] 1. Large working condition fluctuation: the boiling process is not a steady-state process, and the boiling intensity and steam production are dynamically changing, which leads to unstable flow and parameters of secondary steam;

[0007] 2. High control difficulty: for fluctuating boiling conditions, if the compressor operating parameters cannot respond in time, it will lead to system instability. For example, insufficient steam supply may cause compressor surge; too much steam will cause energy waste or system overpressure;

[0008] 3. Insufficient energy efficiency optimization: existing systems mostly use simple PID control, which is difficult to realize real-time optimization of the energy efficiency of the entire system, and cannot always work at the best efficiency point under the premise of ensuring stability.

[0009] Therefore, there is an urgent need for an MVR waste heat recovery system that can adapt to changes in working conditions, intelligently control, and be efficient and stable, to solve the above problems. SUMMARY

[0010] In view of the above problems, the present application provides a MVR-based secondary flash steam waste heat recovery system and method for boiling pot, aiming at solving the problems in the prior art.

[0011] The specific technical solutions are as follows:

[0012] A MVR-based secondary flash steam waste heat recovery system for boiling pot, comprising a boiling pot, a vapor-liquid separator, a steam compressor, a steam reuse device, a flash tank and an ejector, wherein the steam reuse device is arranged inside the boiling pot, a steam outlet of the boiling pot is connected to an input end of the steam reuse device through a pipeline in sequence after passing through an inlet regulating valve, the vapor-liquid separator, the steam compressor and an outlet regulating valve, forming a first steam circuit, and an output end of the steam reuse device is connected to an input end of the vapor-liquid separator through a pipeline in sequence after passing through the flash tank and the ejector, forming a second steam circuit.

[0013] The MVR-based secondary flash steam waste heat recovery system for boiling pot described above further has the following characteristics: the boiling pot is a hollow cylindrical shape, a steam outlet is arranged at the top of the boiling pot, a wort outlet is arranged at the bottom of the boiling pot, a wort inlet is arranged at the side of the boiling pot, the steam reuse device is arranged inside the boiling pot, and both the input end and the output end of the steam reuse device extend to the outside of the boiling pot through the inner wall of the boiling pot.

[0014] The MVR-based secondary flash steam waste heat recovery system for boiling pot described above further has the following characteristics: it further comprises a CIP cleaning pipeline and a cleaning control valve, an output end of the CIP cleaning pipeline is in communication with a steam inlet of the steam reuse device, a cleaning liquid discharge channel is arranged on the steam reuse device, and the cleaning liquid discharge channel extends to the outside of the boiling pot.

[0015] The MVR-based secondary flash steam waste heat recovery system for boiling pot described above further has the following characteristics: it further comprises an acquisition module, the acquisition module comprises a pressure sensor and a temperature sensor, and both the pressure sensor and the temperature sensor are arranged at both ends of the steam compressor.

[0016] The MVR-based secondary flash steam waste heat recovery system for boiling pot described above further has the following characteristics: it further comprises an intelligent control unit, the intelligent control unit adopts a PLC controller, a signal input end of the PLC controller is electrically connected with all the pressure sensors and the temperature sensors, and a signal output end of the PLC controller is electrically connected with the inlet regulating valve, the outlet regulating valve and a frequency converter inside the steam compressor.

[0017] The MVR-based secondary flash steam waste heat recovery system of the boiling pot further has the characteristics that the input end of the steam recycling device is also in communication with an external steam input device, and the input end of the steam recycling device is provided with a pressure input sensor.

[0018] The MVR-based secondary flash steam waste heat recovery system of the boiling pot further has the characteristics that the bottom of the flash tank is provided with a condensed water output port for discharging secondary steam condensed water.

[0019] An MVR-based secondary flash steam waste heat recovery method of a boiling pot, comprising the following steps:

[0020] S1, data acquisition and monitoring, real-time acquisition of steam compressor inlet pressure Pin, inlet temperature Tin, outlet pressure Pout and outlet temperature Tout;

[0021] S2, core parameter calculation, based on the collected data, the intelligent control unit calculates the compression ratio and temperature rise of the current system in real time;

[0022] S3, set value generation and optimization, an energy efficiency optimization model based on historical operation data and thermodynamic model is built in the intelligent control unit, which takes the process requirements of the current boiling pot and the real-time collected steam parameters as input, and dynamically calculates the current optimal target outlet pressure set value Pset and target compression ratio set value CRset;

[0023] S4, multivariate collaborative intelligent control, fine intelligent control of the system according to the set value.

[0024] The MVR-based secondary flash steam waste heat recovery method of the boiling pot further has the characteristics that the specific calculation process in the step S3 is: combining the target outlet pressure set value Pset and the target compression ratio set value CRset, and calculating the error ΔP between the real-time outlet pressure Pout and the target outlet pressure set value Pset, and the error ΔCR between the real-time compression ratio CR and the target compression ratio CRset through the PID proportional operation algorithm, and then the PID proportional operation algorithm resets the new outlet pressure set value P'set and the target compression ratio set value CR'set according to the errors ΔP and ΔCR.

[0025] The MVR-based secondary flash steam waste heat recovery method of the boiling pot further has the characteristics that the step S4 comprises:

[0026] S41, compressor speed main control: taking the target outlet pressure set value Pset as the reference, the frequency converter of the steam compressor is adjusted through the PID algorithm to control its speed;

[0027] S42. Auxiliary regulation of inlet valve: Based on the target compression ratio setpoint CRset, the opening of the inlet regulating valve of the steam compressor is adjusted by the PID algorithm to control the steam flow rate entering the compressor;

[0028] S43, Outlet Valve Pressure Holding Regulation: The outlet regulating valve of the steam compressor is mainly used for isolation and safe pressure relief during system startup, shutdown or abnormal conditions.

[0029] In summary, the beneficial effects of this scheme are:

[0030] The present invention provides a boiler secondary flash steam waste heat recovery system and method based on MVR (Mechanical Vapor Recycling) that directly replaces the large amount of live steam required by the boiler by recovering and improving the quality of the originally wasted secondary flash steam for reuse, thereby improving energy efficiency and significantly reducing cooling water consumption and thermal pollution. The boiler secondary flash steam waste heat recovery system and method based on MVR provided by the present invention has significant energy-saving effects.

[0031] The MVR-based secondary flash steam waste heat recovery system and method for boiling kettles provided by this invention introduces a model- and data-based energy efficiency optimization model. This model dynamically finds and locks the optimal operating point of the system based on real-time operating conditions, rather than fixing it at a certain value, thereby maximizing system energy efficiency. The MVR-based secondary flash steam waste heat recovery system and method for boiling kettles provided by this invention achieves optimal system energy efficiency.

[0032] The MVR-based secondary flash steam waste heat recovery system and method for boiling kettles provided by this invention achieves precise sensing of the MVR system's operating status through multi-point monitoring of inlet / temperature and outlet pressure / temperature, and real-time calculation of compression ratio and temperature rise. By coordinating the control of compressor speed and inlet valves, compressor surge and overload are effectively avoided. The MVR-based secondary flash steam waste heat recovery system and method provided by this invention demonstrates long-term stable operation of the system under fluctuating boiling conditions. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the MVR-based secondary flash steam waste heat recovery system for boiling pots according to the present invention.

[0034] In the diagram: 1. Boiling pot; 2. Steam reuse device; 3. Inlet regulating valve; 4. Gas-liquid separator; 5. Pressure sensor; 6. Temperature sensor; 7. Steam compressor; 8. Outlet regulating valve; 9. Flash tank; 10. Ejector; 11. Pressure input sensor. Detailed Implementation

[0035] The technical solution 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 some embodiments of the present invention, and not all 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.

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0037] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0038] Figure 1 This is a schematic diagram of the waste heat recovery system for secondary flash steam in a boiling pot based on MVR according to the present invention. Figure 1 As shown, the MVR-based secondary flash steam waste heat recovery system and method for boiling pots includes a boiling pot 1, a vapor-liquid separator, a steam compressor 7, a steam reuse device 2, a flash tank 9, and an ejector 10. The steam reuse device 2 is located inside the boiling pot 1. The steam outlet of the boiling pot 1 is connected to the inlet regulating valve 3, the vapor-liquid separator, the steam compressor 7, and the outlet regulating valve 8 in sequence through pipelines, and finally connected to the input end of the steam reuse device 2 to form a first steam circuit. The output end of the steam reuse device 2 is connected to the flash tank 9 and the ejector 10 in sequence through pipelines, and finally connected to the input end of the vapor-liquid separator 4 to form a second steam circuit.

[0039] In the above embodiment, the boiling pot 1 is a hollow cylindrical shape. The top of the boiling pot 1 is provided with a steam outlet, the bottom of the boiling pot 1 is provided with a wort outlet, and the side of the boiling pot 1 is provided with a wort inlet. The steam reuse device 2 is located inside the boiling pot 1, and both the input end and the output end of the steam reuse device 2 extend through the inner wall of the boiling pot 1 to its outside.

[0040] In the above embodiment, a CIP cleaning pipe and a cleaning control valve are also included. The output end of the CIP cleaning pipe is connected to the steam inlet of the steam reuse device 2. The steam reuse device 2 is provided with a cleaning liquid discharge channel, which extends to the outside of the boiling pot 1.

[0041] In the above embodiments, a data acquisition module is also included, which includes a pressure sensor 5 and a temperature sensor 6. The input and output ends of the steam compressor 7 are respectively equipped with a pressure sensor 5 and a temperature sensor 6.

[0042] In the above embodiments, an intelligent control unit is also included. The intelligent control unit adopts a PLC controller. The signal input terminal of the PLC controller is electrically connected to all pressure sensors 5 and temperature sensors 6. The signal output terminal of the PLC controller is electrically connected to the inlet regulating valve 3, the outlet regulating valve 8, and the frequency converter inside the steam compressor 7.

[0043] In the above embodiment, the input end of the steam reuse device 2 is also connected to an external steam input device, and a steam pressure input sensor 11 is provided at the input end of the steam reuse device 2.

[0044] In the above embodiment, the bottom of the flash tank 9 is provided with a condensate outlet for discharging secondary steam condensate.

[0045] A method for recovering waste heat from secondary flash steam in a boiling kettle based on MVR includes the following steps:

[0046] S1. Data acquisition and monitoring: Real-time acquisition of steam compressor 7 inlet pressure Pin, inlet temperature Tin, outlet pressure Pout, and outlet temperature Tout;

[0047] S2. Core parameter calculation: Based on the collected data, the intelligent control unit calculates the current system's compression ratio Pout / Pin and temperature rise ΔT = Tout - Tin in real time.

[0048] S3. Setpoint generation and optimization: The intelligent control unit has a built-in energy efficiency optimization model based on historical operating data and thermodynamic model. The model takes the current process requirements of boiling pot 1 and the real-time collected steam parameters as input to dynamically calculate the current optimal target outlet pressure setpoint Pset and target compression ratio setpoint CRset.

[0049] S4. Multi-variable collaborative intelligent control, which performs refined intelligent control of the system based on the set value.

[0050] In the above embodiment, the specific calculation process in step S3 is as follows: combining the target outlet pressure setpoint Pset and the target compression ratio setpoint CRset, and using the PID proportional calculation algorithm to calculate the error ΔP between the real-time outlet pressure Pout and the target outlet pressure setpoint Pset, and the error ΔCR between the real-time compression ratio CR and the target compression ratio CRset, and then the PID proportional calculation algorithm resets the new outlet pressure setpoint P′set and the target compression ratio setpoint CR′set according to the errors ΔP and ΔCR.

[0051] In the above embodiment, step S4 includes:

[0052] S41, Compressor speed control: Based on the target outlet pressure setpoint Pset, the frequency converter of steam compressor 7 is adjusted through PID algorithm to control its speed;

[0053] S42. Auxiliary regulation of inlet valve: Based on the target compression ratio setpoint CRset, the opening of the inlet regulating valve 3 of the steam compressor 7 is adjusted by the PID algorithm to control the steam flow rate entering the compressor;

[0054] S43, Outlet Valve Pressure Holding Regulation: The outlet regulating valve 8 of the steam compressor 7 is mainly used for isolation and safe pressure relief during system startup, shutdown or abnormal conditions.

[0055] Working principle: In the initial stage of use, the boiling pot 1 begins to generate secondary steam. The inlet pressure sensor 5 detects the pressure, and the intelligent control unit slowly opens the inlet regulating valve 3 and the outlet regulating valve 8, and starts the steam compressor 7 to run at a low speed;

[0056] During normal operation, the system continuously monitors the inlet pressure sensor 5Pin, the inlet temperature sensor 6Tin, the outlet pressure sensor 5Pout, and the outlet temperature sensor 6Tout. When the boiling intensity increases and the amount of secondary steam increases, Pin rises.

[0057] The energy efficiency optimization model recalculates and gives a new, slightly lower target compression ratio CRset and a new target outlet pressure Pset based on the rising Pin and current process requirements.

[0058] The PLC controller compares the current Pout with the new Pset. If Pout is too low, it increases the compressor speed and increases the work done, so that Pout tends to Pset.

[0059] Compare the real-time compression ratio Pout / Pin with the new CRset. Since Pin has increased, the real-time compression ratio will temporarily decrease. To bring it back to the new, more optimal CRset, the controller will appropriately open the inlet regulating valve 3, increasing the intake air volume. This increased intake air volume also helps maintain the compressor in its high-efficiency range, preventing surge.

[0060] By coordinating the adjustment of rotational speed and valve opening, the system quickly reached equilibrium under new operating conditions with a larger steam volume and operated at the optimized energy efficiency point.

[0061] When the boiling intensity decreases, the control process is reversed, adapting by reducing the speed and closing the inlet valve to maintain system stability and efficiency.

[0062] When boiling pot 1 stops production, the CIP cleaning regulating valve automatically opens, cleaning the steam side of the steam reuse device 2.

[0063] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the content of this specification should be included within the protection scope of the present invention.

Claims

1. A secondary flash steam waste heat recovery system for boiling kettles based on MVR, characterized in that, The system includes a boiling pot (1), a vapor-liquid separator, a steam compressor (7), a steam reuse device (2), a flash tank (9), and an ejector (10). The steam reuse device (2) is located inside the boiling pot (1). The steam outlet of the boiling pot (1) is connected to the inlet regulating valve (3), the vapor-liquid separator, the steam compressor (7), and the outlet regulating valve (8) in sequence through pipelines, and finally connected to the input end of the steam reuse device (2) to form a first steam circuit. The output end of the steam reuse device (2) is connected to the flash tank (9) and the ejector (10) in sequence through pipelines, and finally connected to the input end of the vapor-liquid separator (4) to form a second steam circuit.

2. The MVR-based secondary flash steam waste heat recovery system for boiling kettles according to claim 1, characterized in that, The boiling pot (1) is a hollow cylindrical shape. The boiling pot (1) has a steam outlet at the top, a wort outlet at the bottom, and a wort inlet on the side. The steam reuse device (2) is located inside the boiling pot (1), and both the input and output ends of the steam reuse device (2) extend through the inner wall of the boiling pot (1) to its outside.

3. The MVR-based secondary flash steam waste heat recovery system for boiling kettles according to claim 2, characterized in that, It also includes a CIP cleaning pipe and a cleaning control valve. The output end of the CIP cleaning pipe is connected to the input end of the steam reuse device (2). The steam reuse device (2) is provided with a cleaning liquid discharge channel, which extends to the outside of the boiling pot (1).

4. The MVR-based secondary flash steam waste heat recovery system for boiling kettles according to claim 1, characterized in that, It also includes a data acquisition module, which includes a pressure sensor (5) and a temperature sensor (6). The input and output ends of the steam compressor (7) are respectively equipped with the pressure sensor (5) and the temperature sensor (6).

5. A secondary flash steam waste heat recovery system for boiling kettles based on MVR according to claim 4, characterized in that, It also includes an intelligent control unit, which is a PLC controller. The signal input terminal of the PLC controller is electrically connected to all the pressure sensors (5) and the temperature sensors (6). The signal output terminal of the PLC controller is electrically connected to the inlet regulating valve (3), the outlet regulating valve (8), and the frequency converter inside the steam compressor (7).

6. The MVR-based secondary flash steam waste heat recovery system for boiling kettles according to claim 1, characterized in that, The input end of the steam reuse device (2) is also connected to an external steam input device, and a pressure input sensor (11) is provided at the input end of the steam reuse device (2).

7. The MVR-based secondary flash steam waste heat recovery system for boiling kettles according to claim 1, characterized in that, The bottom of the flash tank (9) is provided with a condensate outlet for discharging secondary steam condensate.

8. A method for recovering waste heat from secondary flash steam in a boiling kettle based on MVR, characterized in that, Controlling the system as described in any one of claims 1-6 includes the following steps: S1. Data acquisition and monitoring: Real-time acquisition of steam compressor (7) inlet pressure Pin, inlet temperature Tin, outlet pressure Pout, and outlet temperature Tout. S2. Core parameter calculation: Based on the collected data, the intelligent control unit calculates the current system's compression ratio (Pout / Pin) and temperature rise (ΔT = Tout - Tin) in real time. S3. Setpoint generation and optimization: The intelligent control unit has a built-in energy efficiency optimization model based on historical operating data and thermodynamic model. The model takes the current process requirements of the boiling pot (1) and the real-time collected steam parameters as input to dynamically calculate the current optimal target outlet pressure setpoint Pset and target compression ratio setpoint CRset. S4. Multi-variable collaborative intelligent control, which performs refined intelligent control of the system based on the set value.

9. A method for recovering waste heat from secondary flash steam in a boiling pot based on MVR, as described in claim 8, characterized in that: The specific calculation process in step S3 is as follows: combining the target outlet pressure setpoint Pset and the target compression ratio setpoint CRset, and using the PID proportional calculation algorithm to calculate the error ΔP between the real-time outlet pressure Pout and the target outlet pressure setpoint Pset, and the error ΔCR between the real-time compression ratio CR and the target compression ratio CRset, the PID proportional calculation algorithm then resets the new outlet pressure setpoint P′set and the target compression ratio setpoint CR′set based on the errors ΔP and ΔCR.

10. A method for recovering waste heat from secondary flash steam in a boiling pot based on MVR, as described in claim 5, characterized in that: Step S4 includes: S41, compressor speed control: Based on the target outlet pressure setpoint Pset, the frequency converter of the steam compressor (7) is adjusted by PID algorithm to control its speed; S42, Auxiliary regulation of inlet valve: Based on the target compression ratio set value CRset, the opening of the inlet regulating valve (3) of the steam compressor (7) is adjusted by PID algorithm to control the steam flow rate entering the compressor; S43, outlet valve pressure regulation: Steam compressor (7) outlet regulating valve (8) is mainly used for isolation and safe pressure relief during system startup, shutdown or abnormal conditions.

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