Waste heat recovery and control system and method of anti-interference liquid deslagging boiler

Abstract

The invention relates to a waste heat recovery and control system and method of an anti-interference liquid deslagging boiler. The system comprises a first-stage heat exchanger, a second-stage heat exchanger, an air preheater and a control system. The first-stage heat exchanger and the second-stage heat exchanger are used for exchanging heat between the liquid slag and a heat exchange medium; the air preheater is used for preheating air by a heat exchange medium, distributing the air flow after heat exchange and re-preheating the distributed air; a plurality of temperature sensors, a plurality of pressure sensors and a plurality of flow sensors are arranged at specific positions, and a control system is connected with the temperature sensors, the pressure sensors, the flow sensors, a liquid slag conveying pump, an air fan, a three-way electromagnetic valve, an electromagnetic valve a and an electromagnetic valve b. The rotating speed of the liquid slag conveying pump, the air volume of the air fan and the opening degrees of the three-way electromagnetic valve, the electromagnetic valve a and the electromagnetic valve b are regulated and controlled. The liquid slag waste heat recovery rate and the air preheating effect are improved, and the energy utilization rate and the anti-interference operation stability of the liquid slag discharging boiler are enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid slagging boilers, and in particular relates to a waste heat recovery and control system and method for an anti-interference liquid slagging boiler. Background Art

[0002] Liquid slag boilers occupy a key position in many industrial energy-consuming sectors due to their advantages such as strong fuel adaptability and high combustion efficiency. The high-temperature liquid slag generated during their operation contains a large amount of waste heat. However, traditional liquid slag boilers have many shortcomings in terms of liquid slag waste heat recovery and air preheating. On the one hand, the irrational design of the liquid slag waste heat recovery device leads to a low waste heat recovery rate and a large amount of heat energy is wasted. On the other hand, the lack of effective coordination between the air preheating system and the liquid slag waste heat recovery system not only affects the overall thermal efficiency of the boiler, but may also cause fluctuations in operating parameters and untimely responses due to interference from load changes, thereby causing equipment failure. In addition, the lack of precise intelligent control during system operation makes it difficult to adjust operating parameters in real time according to different boiler operating conditions, further reducing the stability of system operation and the efficiency of energy utilization.

[0003] In summary, developing an efficient waste heat recovery and control system and method for anti-interference liquid slag discharge boilers, forming efficient heat exchange, intelligent operation and maintenance, and clean and environmentally friendly technologies, has become an urgent task for industrial energy conservation, emission reduction, and green development. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a system and method for utilizing waste heat from a liquid slag discharge boiler, which improves the boiler's energy utilization rate and anti-interference operation stability, and reduces environmental pollution.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a waste heat recovery and control system for an anti-interference liquid slag discharge boiler, comprising an air preheater, a first inlet of the air preheater being connected to a secondary heat exchanger through a first delivery pipe, the secondary heat exchanger being further connected to an air blower through a cold air delivery pipe, the first delivery pipe being further connected to a second delivery pipe through a three-way solenoid valve, a first outlet of the air preheater being connected to an air mixing device, the second delivery pipe being also connected to the air mixing device, a second inlet of the air preheater being connected to an exhaust pipe of the slag discharge boiler, and a second outlet of the air preheater being discharged after dust removal, the slag discharge boiler being connected to the liquid slag delivery pipe through a liquid slag delivery pump, the liquid slag delivery pipe being connected to a primary heat exchanger, the primary heat exchanger and the secondary heat exchanger being connected through a third delivery pipe and a fourth delivery pipe, for delivering the liquid slag heat from the primary heat exchanger to the secondary heat exchanger for heat exchange with the cold air delivered into the secondary heat exchanger, a solenoid valve a being provided on the third delivery pipe, and a solenoid valve b being provided on the fourth delivery pipe;

[0007] Multiple temperature sensors are respectively arranged on the slag discharge boiler, the inlet and outlet of the first-stage heat exchanger, the first inlet and outlet of the air preheater, and the second inlet and outlet of the air preheater;

[0008] A plurality of pressure sensors are respectively arranged on the cold air conveying pipe, the first conveying pipe, the second conveying pipe and the liquid slag conveying pipe;

[0009] A plurality of flow sensors are respectively arranged on the liquid slag conveying pipe, the first conveying pipe, the second conveying pipe, the third conveying pipe and the fourth conveying pipe;

[0010] The control system is respectively connected to multiple temperature sensors, multiple pressure sensors, multiple flow sensors, a liquid slag conveying pump, an air fan, a three-way solenoid valve, a solenoid valve a and a solenoid valve b, and is used to control the speed of the liquid slag conveying pump, the air volume of the air fan and the opening of the three-way solenoid valve, the solenoid valve a and the solenoid valve b according to multiple temperatures, multiple pressures, multiple flow rates and the heat load in the slag discharge boiler.

[0011] The first-stage liquid-slag heat exchanger is a spiral-feed heat exchanger. The heat exchange medium is located inside the tubes, and the liquid slag is continuously rotated and transported outside the tubes by a spiraling device, which increases the contact area between the liquid slag and the heat exchange medium and increases the heat transfer capacity. The second-stage heat exchanger exchanges heat between the heat exchange medium and the air. This cascaded energy utilization method not only avoids direct contact between the liquid slag and the air, ensuring that the hot air is not contaminated by the liquid slag, but also effectively reduces energy losses caused by large temperature differences during heat exchange.

[0012] The liquid slag conveying pipeline must not only be resistant to high temperatures, but also have excellent thermal insulation performance. A multi-layer composite insulation structure can be adopted, such as an inner layer of ceramic fiber material, an outer layer of stainless steel plate, and rock wool insulation material filled in the middle to reduce heat loss of liquid slag during transportation.

[0013] The cold air duct must ensure sufficient air intake and minimal resistance. This can be achieved by optimizing its diameter and shape. The cold air duct is connected to an air filter with a multi-stage filtration structure. This includes a primary filter to remove large particles, a medium-efficiency filter to intercept smaller particles, and a high-efficiency filter to remove fine dust, ensuring clean air entering the air preheater.

[0014] The structure of the secondary heat exchanger is conducive to sufficient heat exchange. The heat exchange tubes of the secondary heat exchanger can adopt a finned tube structure to increase the heat exchange area between air and heat exchange medium.

[0015] Each temperature sensor uses a thermocouple sensor, which can accurately measure temperature changes in high temperature environments.

[0016] Electromagnetic flowmeters can be used as flow sensors to accurately measure liquid slag and air flow. The data acquisition module utilizes a high-speed data acquisition card, enabling rapid and accurate acquisition of sensor data and transmission to the controller. The control system filters and amplifies the collected data to remove noise, improve data accuracy, and minimize the impact of data fluctuations on control decisions.

[0017] The pressure sensor adopts piezoresistive sensor, which has high pressure measurement accuracy and response speed. It is installed in the part where pressure fluctuation is likely to occur to ensure the safe operation of the system.

[0018] Preferably, a liquid slag collecting device is further provided between the slag discharge boiler and the primary heat exchanger, the slag discharge boiler is connected to the liquid slag collecting device, and the liquid slag collecting device is connected to the liquid slag conveying pipe via a liquid slag conveying pump.

[0019] As the starting part of the system, the liquid slag collection device must have good high temperature resistance and corrosion resistance, and be able to effectively collect high-temperature liquid slag and temporarily store it.

[0020] Preferably, the liquid slag conveying pipe is a device made of multiple layers of composite thermal insulation material, and the multiple layers of composite thermal insulation material are ceramic fiber, rock wool and stainless steel plate from the inside to the outside.

[0021] Preferably, the second outlet of the air preheater is connected to the dust removal device, the induced draft fan, the desulfurization purification device and the chimney in sequence through pipelines.

[0022] Preferably, the heat exchange medium flowing in the third and fourth delivery pipes is thermal oil. The spiral tube structure of the primary heat exchanger enables the liquid slag to flow well outside the tube, enhancing the heat transfer capacity. The heat exchange medium can be a high-temperature stable medium such as thermal oil.

[0023] The present invention also provides a control method for a waste heat recovery and control system of an anti-interference liquid slag discharge boiler, comprising the following steps:

[0024] The liquid slag discharged from the slag discharge boiler is sent to the first-stage heat exchanger through the liquid slag conveying pipe and the liquid slag conveying pump to realize heat exchange between the liquid slag and the heat exchange medium. The heat exchange medium after absorbing heat exchanges heat with the cold air sent into the second-stage heat exchanger in the second-stage heat exchanger.

[0025] A portion of the heated hot air enters the air preheater through the first conveying pipe, and exchanges heat with the boiler flue gas sent into the air preheater by the slagging boiler in the air preheater. The reheated air is mixed with the other portion of the heated hot air in the air mixing device, and the mixed hot air is sent to the slagging boiler for reuse. The boiler flue gas after heat exchange is discharged after dust removal.

[0026] The control system adjusts the liquid slag conveying pump speed, fan air volume, the opening of the three-way solenoid valve, solenoid valve a and solenoid valve b according to the temperature measurement values of each temperature sensor, the pressure measurement values of each pressure sensor, the flow measurement values of each flow sensor and the heat load in the slag discharge boiler received in real time, so as to keep the system in the best operating state at all times.

[0027] Preferably, the control system regulates the liquid slag conveying pump speed, the fan air volume, the openings of the three-way solenoid valve, the solenoid valve a, and the solenoid valve b according to the temperature measurement values of each temperature sensor, the pressure measurement values of each pressure sensor, the flow measurement values of each flow sensor, and the heat load in the slag discharge boiler received in real time, so as to keep the system in an optimal operating state at all times;

[0028] According to the deviation between the set value and the measured value of each parameter, the liquid slag conveying pump speed, fan air volume, three-way solenoid valve, solenoid valve a and solenoid valve b are adjusted proportionally. The steady-state error is eliminated by integral adjustment of the deviation to ensure that the parameter is finally stabilized at the set value. The deviation change rate is differentially adjusted to achieve early action, suppress the sharp fluctuation of the parameter, enhance system stability, and achieve boiler operation stability.

[0029] Preferably, when adjusting the liquid slag conveying pump speed, fan air volume, three-way solenoid valve, solenoid valve a and solenoid valve b openings:

[0030] According to the cold air temperature of the air preheater, the temperature of the air heated by the air preheater, the constant pressure specific heat capacity of the air and the air flow rate, the heat balance equation of the air preheating unit is established to obtain the heat absorbed by the air;

[0031] Based on the initial temperature of the liquid slag discharged from the slag discharge boiler, the outlet temperature of the liquid slag after waste heat recovery, the constant pressure specific heat capacity of the liquid slag and the liquid slag flow rate, the heat balance equation of the liquid slag waste heat recovery system is established to obtain the heat released by the liquid slag;

[0032] Establish an energy conservation equation. Based on the heat absorbed by the air, the heat released by the liquid slag, and the heat loss of the boiler itself, the sum of the effective heat removed by the steam or hot water generated by the boiler is equal to the total heat input by the boiler fuel combustion. With the goal of improving the overall thermal efficiency of the boiler, reducing fuel consumption, and meeting the system operation constraints, efficient energy utilization is achieved by maximizing the total thermal efficiency of the boiler.

[0033] The temperature setting value and flow setting value are determined based on the heat absorbed by the air and the heat released by the liquid slag corresponding to the maximum overall thermal efficiency of the boiler.

[0034] Among them, the heat balance equation of the air preheating unit is established:

[0035] Q air =F air Cp,air (T air,out -T air,in )=F smoke C p,smoke (T smoke,in -T smoke,out );

[0036] Among them, Q air is the heat absorbed by the air, C p,air is the constant pressure specific heat capacity of air, C p,smoke is the constant pressure specific heat capacity of flue gas, F air is the air flow rate, F smoke is the flue gas flow rate, T air，in is the cold air temperature of the air preheater, T air，out is the air temperature after being heated by the air preheater, T smoke，in is the flue gas temperature discharged from the boiler and entering the air preheater, T smoke，out is the flue gas temperature after passing through the air preheater;

[0037] Establish the heat balance equation of the liquid slag waste heat recovery system:

[0038] Q slag =F slag C p,slag (T slag,in -T slag,out )=F water C p,water (T water,out -T water,in );

[0039] Among them, Q slag Heat released by liquid slag, C p,slag is the constant pressure specific heat capacity of liquid slag, C p,water is the specific heat capacity of water at constant pressure, F water is the heat transfer medium flow rate, F slag is the liquid slag flow rate, T water,in is the inlet temperature of the heat transfer medium water, T water,out is the outlet temperature of the heat transfer medium water, T slag,in is the initial temperature of the liquid slag discharged from the boiler, T slag,out is the outlet temperature of liquid slag after waste heat recovery;

[0040] Considering the overall energy conservation of the boiler, the energy conservation equation is established:

[0041] Q input =Q output +Q air +Q slag +Q loss ;

[0042] Among them, Q inputis the total heat input from boiler fuel combustion, Q output The effective heat taken away by the boiler to generate steam or hot water, Q loss Other energy consumption is due to heat loss of the boiler body;

[0043] With the goal of improving the overall thermal efficiency of the boiler, reducing fuel consumption, and meeting the system operation constraints, efficient energy utilization is achieved by maximizing the total thermal efficiency of the boiler. The optimized total thermal efficiency objective function is constructed as follows:

[0044]

[0045] Among them, η total is the total thermal efficiency of the boiler.

[0046] Preferably, the constraints are as follows:

[0047] T air,out,min ≤T air,out ≤T air,out,max ;

[0048] T slag,out,min ≤T slag,out ≤T slag,out,max ;

[0049] T smoke,out ≥T dewpoint +ΔT;

[0050] F air,min ≤F air ≤F air,max ;

[0051] F slag,min ≤F slag ≤F slag,max ;

[0052] Where T air，out，max The maximum temperature of the air after being heated by the air preheater; T air，out The temperature of the air after being heated by the air preheater; T air，out，min The lowest temperature of the air after being heated by the air preheater, T slag，out，max is the maximum temperature of liquid slag outlet after waste heat recovery, T slag，out，min is the lowest temperature of liquid slag outlet after waste heat recovery, T slag,out T is the outlet temperature of liquid slag after waste heat recovery; smoke,out is the flue gas temperature after passing through the air preheater, T dewpoint is the flue gas dew point temperature after passing through the air preheater, ΔT is the set temperature margin, F air，max is the maximum air flow rate, F air is the air flow rate; F air，min is the minimum air flow rate, Fslag，max is the maximum flow rate of liquid slag, F slag,min is the minimum flow rate of liquid slag; F slag is the liquid slag flow rate.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] This invention utilizes temperature, pressure, and flow sensors to comprehensively monitor operating parameter values in real time. The control system utilizes an adaptive, anti-interference, collaborative optimization algorithm to deeply analyze and rapidly process boiler operating data, thereby accurately regulating the liquid slag conveying pump speed, air blower volume, and heat exchange medium flow rate. This not only ensures the system's automatic adaptation and stable operation under varying operating conditions, but also allows for flexible adjustments based on actual needs, avoiding energy waste and further enhancing the refinement and intelligence of energy utilization.

[0055] This invention achieves efficient, cascaded energy utilization by tightly coupling the furnace waste heat recovery unit with the air preheating unit. The primary heat exchanger efficiently recovers the waste heat from the liquid slag and transfers it to the heat exchange medium. The high-temperature medium then fully preheats the air in the secondary heat exchanger. The control system intelligently controls the hot air flow rate, allowing it to enter the boiler for reuse based on boiler load requirements. This significantly improves combustion performance and reduces fuel consumption, significantly increasing the energy efficiency of the entire system and reducing energy costs for the enterprise.

[0056] The control system proposed by this invention can also adjust various equipment parameters in real time based on boiler operating conditions, effectively preventing damage to equipment caused by excessive thermal stress and abnormal over-temperature conditions. For example, when boiler load fluctuates, the liquid slag flow rate and air flow rate can be adjusted promptly to prevent thermal deformation or damage to the primary heat exchanger, air preheater, and secondary heat exchanger caused by sudden temperature changes. This significantly extends the service life of various equipment in the waste heat recovery unit and air preheating system, reduces equipment maintenance and replacement costs, and improves the overall reliability and stability of the system, providing a strong guarantee for the company's long-term stable production. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a schematic diagram of the efficient waste heat recovery and control system of the adaptive anti-interference liquid slag discharge boiler provided by the present invention.

[0058] Figure 2 A waste heat recovery control system for a liquid slagging boiler is provided in one embodiment of the present invention.

[0059] Reference numerals

[0060] 1. Slag discharge boiler; 2. Primary heat exchanger; 3. Secondary heat exchanger; 4. Air preheater; 5. Dust removal device; 6. Induced draft fan; 7. Desulfurization and purification device; 8. Chimney; 9. Air mixing device. L1 is the air in the delivery pipeline after mixing; L2 is the air from the secondary heat exchanger; L3 is the air from the air preheater; L4 is the air after the secondary heat exchanger; L5 is the flue gas after cooling in the air preheater; L6 is the high-temperature heat exchange medium at the outlet of the primary heat exchanger; L7 is the low-temperature heat exchange medium at the inlet of the primary heat exchanger. DETAILED DESCRIPTION

[0061] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0062] The inventors have found that the liquid slag discharge boiler has problems in terms of low liquid slag waste heat recovery rate, poor coordination between the air preheating system and the liquid slag waste heat recovery system, lack of precise intelligent control of the system operation, and inability to adjust parameters in real time according to the working conditions. In order to solve the above problems, the present invention has designed an adaptive anti-interference liquid slag discharge boiler high-efficiency waste heat recovery and control system. The system includes three core parts: a waste heat recovery unit, an air preheating unit and a control system. Through the coordinated work of each unit, efficient recovery of liquid slag waste heat and sufficient preheating of air are achieved. In intelligent control, data is collected with the help of temperature sensors, pressure sensors, and flow sensors, and the data is transmitted to the controller using a data acquisition module. The controller uses an anti-interference collaborative optimization algorithm to conduct in-depth analysis of the data, and then accurately controls the opening of the solenoid valve through the actuator to achieve real-time adjustment of operating parameters according to different working conditions of the boiler, effectively improve the liquid slag waste heat recovery rate and air preheating effect, enhance the energy utilization rate of the liquid slag discharge boiler, anti-interference operation stability and reduce environmental pollution.

[0063] like Figures 1 and 2As shown, the present invention provides a waste heat recovery and control system for an anti-interference liquid slag discharge boiler, wherein the first inlet of the air preheater 4 is connected to the secondary heat exchanger 3 through a first conveying pipe, the secondary heat exchanger 3 is also connected to the air blower through a cold air conveying pipe, the first conveying pipe is also connected to the second conveying pipe through a three-way solenoid valve, the first outlet of the air preheater 4 is connected to an air mixing device 9, the second conveying pipe is also connected to the air mixing device 9, the second inlet of the air preheater 4 is connected to the exhaust pipe of the slag discharge boiler 1, and the second outlet of the air preheater 4 is discharged after dust removal, the slag discharge boiler 1 is connected to the liquid slag conveying pipe through a liquid slag conveying pump, the liquid slag conveying pipe is connected to the primary heat exchanger 2, and the primary heat exchanger 2 and the secondary heat exchanger 3 are connected through a third conveying pipe and a fourth conveying pipe, which are used to convey the liquid slag heat from the primary heat exchanger 2 to the secondary heat exchanger 3 for heat exchange with the cold air sent into the secondary heat exchanger 3, the third conveying pipe is provided with a solenoid valve a, and the fourth conveying pipe is provided with a solenoid valve b;

[0064] The cold air delivery pipe connected to the air blower must ensure sufficient air intake and low resistance. This can be achieved by optimizing the pipe diameter and shape. A gas filter is installed on the cold air delivery pipe. The gas filter uses a multi-stage filtration structure, including a primary filter to remove large particles, a medium-efficiency filter to intercept smaller particles, and a high-efficiency filter to remove fine dust, ensuring the clean air entering the air preheater.

[0065] The air L1 output after mixing at the air mixing device 9 is the air conveying pipeline after mixing, the air L2 of the secondary heat exchanger comes from the second conveying pipe, the air L3 of the air preheater comes from the first conveying pipe, the air L4 after the secondary heat exchanger comes from the secondary heat exchanger 3 after heat exchange, L5 comes from the second discharge outlet of the air preheater 5, the high-temperature heat exchange medium L6 at the outlet of the first heat exchanger comes from the third conveying pipe, and the low-temperature heat exchange medium L7 at the inlet of the first heat exchanger comes from the fourth conveying pipe.

[0066] Multiple temperature sensors are respectively arranged on the slag discharge boiler 1, the inlet and outlet of the primary heat exchanger 2, the first inlet and outlet of the air preheater 4, and the second inlet and outlet of the air preheater 4;

[0067] Each temperature sensor uses a thermocouple sensor, which can accurately measure temperature changes in high temperature environments. Its installation position has been precisely calculated to ensure that it can truly reflect the temperature conditions of each key part;

[0068] Multiple pressure sensors are respectively installed on the cold air conveying pipe, the first conveying pipe, the liquid slag conveying pipe and the second conveying pipe; each pressure sensor adopts a piezoresistive sensor with high pressure measurement accuracy and response speed, and is installed in the position where pressure fluctuations are likely to occur.

[0069] Multiple flow sensors are respectively arranged on the liquid slag conveying pipe, the first conveying pipe, the second conveying pipe, the third conveying pipe and the fourth conveying pipe; each flow sensor can use an electromagnetic flowmeter to accurately measure the liquid slag and air flow.

[0070] The control system is respectively connected to multiple temperature sensors, multiple pressure sensors, multiple flow sensors, a liquid slag conveying pump, an air fan, a three-way solenoid valve, a solenoid valve a and a solenoid valve b, and is used to control the speed of the liquid slag conveying pump, the air volume of the air fan and the opening of the three-way solenoid valve, the solenoid valve a and the solenoid valve b according to multiple temperatures, multiple pressures, multiple flow rates and the heat load in the slag discharge boiler 1.

[0071] The control system uses a high-speed data acquisition card to quickly and accurately collect sensor data and transmit it to the controller. The control system filters and amplifies the collected data to remove noise interference, improve data accuracy, and reduce the impact of data fluctuations on control decisions.

[0072] The first-stage heat exchanger 2 utilizes a spiral-feed heat exchanger structure. The heat exchange medium resides within the tubes, while a spiraling mechanism on the outside of the tubes continuously rotates and transports the liquid slag, increasing the contact area between the liquid slag and the heat exchange medium and increasing the heat transfer capacity. The second-stage heat exchanger 3 exchanges heat between the heat exchange medium and air. This cascaded energy utilization prevents direct contact between the liquid slag and air, ensuring that the hot air is not contaminated by the liquid slag. It also effectively reduces energy losses caused by excessive temperature differences during heat exchange. The spiral tube structure of the first-stage heat exchanger 2 ensures smooth flow of the liquid slag outside the tubes, enhancing heat transfer capabilities. The heat exchange medium can be a high-temperature, stable medium such as thermal oil.

[0073] The structural design of the primary heat exchanger 2 facilitates efficient heat exchange. Its heat exchange tubes utilize a finned tube structure to increase the heat exchange area between the air and the heat exchange medium. The third and fourth delivery pipes are rationally designed based on the layout of the boiler's combustion area, and the combination of solenoid valves a and b ensures uniform and precise air distribution.

[0074] Specifically, a liquid slag collection device is provided between the slag discharge boiler 1 and the primary heat exchanger 2. The slag discharge boiler 1 is connected to the liquid slag collection device, which is connected to a liquid slag delivery pipe via a liquid slag delivery pump. As the initial component of the system, the liquid slag collection device must possess excellent high-temperature and corrosion resistance, effectively collecting and temporarily storing high-temperature liquid slag.

[0075] Specifically, the liquid slag conveying pipe is a device made of multiple layers of composite thermal insulation materials, and the multiple layers of composite thermal insulation materials are ceramic fiber, rock wool and stainless steel plate from the inside to the outside.

[0076] The liquid slag conveying pipeline must not only be resistant to high temperatures, but also have excellent thermal insulation properties. It can be made of a device made of multi-layer composite insulation materials, such as an inner layer of ceramic fiber material, an outer layer of stainless steel plate, and rock wool insulation material filled in the middle to reduce heat loss of liquid slag during transportation.

[0077] Specifically, the second outlet of the air preheater 4 is connected to the dust removal device 4, the induced draft fan 6, the desulfurization purification device 7 and the chimney 8 in sequence through pipelines.

[0078] Specifically, the heat exchange medium flowing in the third conveying pipe and the fourth conveying pipe is heat transfer oil, the first-stage heat exchanger 2 is a spiral heat exchanger, the inside of the spiral heat exchanger tube is heat exchange medium, and the outside of the spiral heat exchanger tube is provided with a spiral device for continuously turning and conveying the liquid slag.

[0079] The invention provides a control method for waste heat recovery and control system of an anti-interference liquid slag discharge boiler, comprising the following steps:

[0080] The liquid slag discharged from the slag discharge boiler 1 is sent to the primary heat exchanger 2 through the liquid slag conveying pipe and the liquid slag conveying pump to realize heat exchange between the liquid slag and the heat exchange medium. The heat exchange medium after absorbing heat exchanges heat with the cold air sent into the secondary heat exchanger 3 in the secondary heat exchanger 3;

[0081] A portion of the heated hot air enters the air preheater 4 through the first conveying pipe, and exchanges heat with the boiler flue gas sent into the air preheater 4 by the slag discharge boiler 1 in the air preheater 4. The reheated air is mixed with the other portion of the heated hot air in the air mixing device 9. The mixed hot air is sent to the slag discharge boiler 1 for reuse. The boiler flue gas after heat exchange is discharged after dust removal.

[0082] The control system adjusts the liquid slag conveying pump speed, fan air volume, and the openings of the three-way solenoid valve, solenoid valve a, and solenoid valve b based on the temperature measurement values of each temperature sensor, the pressure measurement values of each pressure sensor, and the flow measurement values of each flow sensor received in real time, as well as the heat load in the slag discharge boiler 1, so as to keep the system in the best operating state at all times.

[0083] Specifically, the control system regulates the liquid slag conveying pump speed, fan air volume, and the openings of the three-way solenoid valve, solenoid valve a, and solenoid valve b based on the temperature measurement values of each temperature sensor, the pressure measurement values of each pressure sensor, and the flow measurement values of each flow sensor received in real time, as well as the heat load in the slag discharge boiler 1, so that the system is always in the best operating state:

[0084] According to the deviation between the set value and the measured value of each parameter, the liquid slag conveying pump speed, fan air volume, three-way solenoid valve, solenoid valve a and solenoid valve b are adjusted proportionally. The steady-state error is eliminated by integral adjustment of the deviation to ensure that the parameter is finally stabilized at the set value. The deviation change rate is differentially adjusted to achieve early action, suppress the sharp fluctuation of the parameter, enhance system stability, and achieve boiler operation stability.

[0085] Specifically, when adjusting the liquid slag conveying pump speed, fan air volume, three-way solenoid valve, solenoid valve a and solenoid valve b opening:

[0086] Establish the heat balance equation of the air preheating unit:

[0087] Q air =F air C p,air (T air,out -T air,in )=F smoke C p,smoke (T smoke,in -T smoke,out );

[0088] Among them, Q air is the heat absorbed by the air, C p,air is the constant pressure specific heat capacity of air, C p,smoke is the constant pressure specific heat capacity of flue gas, F air is the air flow rate, F smoke is the flue gas flow rate, T air，in is the cold air temperature of the air preheater, T air，out is the air temperature after being heated by the air preheater, T smoke，in is the flue gas temperature discharged from the boiler and entering the air preheater, T smoke，out is the flue gas temperature after passing through the air preheater;

[0089] Establish the heat balance equation of the liquid slag waste heat recovery system:

[0090] Q slag =F slag C p,slag (T slag,in -T slag,out )=F water C p,water (T water,out -T water,in );

[0091] Among them, Q slag Heat released by liquid slag, C p,slag is the constant pressure specific heat capacity of liquid slag, C p,water is the specific heat capacity of water at constant pressure, F water is the heat transfer medium flow rate, F slagis the liquid slag flow rate, T water,in is the inlet temperature of the heat transfer medium water, T water,out is the outlet temperature of the heat transfer medium water, T slag,in is the initial temperature of the liquid slag discharged from the boiler, T slag,out is the outlet temperature of liquid slag after waste heat recovery;

[0092] Considering the overall energy conservation of the boiler, the energy conservation equation is established:

[0093] Q input =Q output +Q air +Q slag +Q loss ;

[0094] Among them, Q input is the total heat input from boiler fuel combustion, Q output The effective heat taken away by the boiler to generate steam or hot water, Q loss Other energy consumption such as heat loss of the boiler body;

[0095] With the goal of improving the overall thermal efficiency of the boiler, reducing fuel consumption, and meeting the system operation constraints, efficient energy utilization is achieved by maximizing the total thermal efficiency of the boiler. The optimized total thermal efficiency objective function is constructed as follows:

[0096]

[0097] Among them, η total is the total thermal efficiency of the boiler.

[0098] Specifically, the constraints are as follows:

[0099] T air,out,min ≤T air,out ≤T air,out,max ;

[0100] T slag,out,min ≤T slag,out ≤T slag,out,max ;

[0101] T smoke,out ≥T dewpoint +ΔT;

[0102] F air,min ≤F air ≤F air,max ;

[0103] F slag,min ≤F slag ≤F slag,max ;

[0104] Where T air,out,maxThe maximum temperature of the air after being heated by the air preheater; T air,out,min The lowest temperature of the air after being heated by the air preheater, T slag,out,max is the maximum temperature of liquid slag outlet after waste heat recovery, T slog,out,min is the lowest temperature of liquid slag outlet after waste heat recovery, T smoke,out is the flue gas temperature after passing through the air preheater, T dwpoint is the flue gas dew point temperature after passing through the air preheater, ΔT is the set temperature margin, F air,max is the maximum air flow rate, F air,min is the minimum air flow rate, F slag,max is the maximum flow rate of liquid slag, F slag，min is the minimum flow rate of liquid slag.

[0105] Where T air,out The air temperature should meet the burner's requirements to ensure good combustion effect. slag,out It should be higher than the solidification temperature of the liquid slag to avoid solidification of the liquid slag in the waste heat recovery unit and blockage of the pipeline. The temperature requirements of the subsequent liquid slag processing equipment should also be considered. smoke,out Should be higher than the dew point temperature to prevent low temperature corrosion in subsequent flues and equipment; air and F slag It should be reasonably adjusted according to the boiler load and should be within the design flow range of the air preheater and liquid slag waste heat recovery device.

[0106] Adaptive collaborative control strategy formulation: Based on the established heat balance equation, optimization objective function and constraints, the optimization algorithm is used to solve the optimal operating parameters of the air preheater, the first-stage heat exchanger 2 and the second-stage heat exchanger 3 under the current boiler operating conditions, including the air flow rate F air , liquid slag flow F slag , heat transfer medium flow F of waste heat recovery unit water and the associated temperature control setpoints (such as T air,out 、T slag,out wait).

[0107] Based on the optimal parameters obtained, a collaborative control strategy is formulated. By adjusting actuators such as fan speed and valve opening, precise control of the air preheater, primary heat exchanger 2, and secondary heat exchanger 3 is achieved, reducing the impact of load fluctuations on the boiler.

[0108] For the air preheater, the optimal air flow F is calculated based on the air , adjust the speed of the air fan or the opening of the inlet guide vane to ensure that the amount of air entering the air preheater meets the requirements. Use the flue gas damper or bypass flue to adjust the flow rate and heat transfer area distribution of the flue gas in the air preheater 4 to control the flue gas outlet temperature T smoke,out, so that it can meet the requirements of subsequent waste heat recovery and prevention of low-temperature corrosion.

[0109] According to the calculated liquid slag flow F slag and liquid slag outlet temperature F slag,out , adjust the opening of the liquid slag discharge valve and the operating parameters of the waste heat recovery unit to ensure that the waste heat of the liquid slag is fully recovered, while ensuring the normal discharge and treatment of the liquid slag.

[0110] According to the heat transfer medium outlet temperature T water,out , controls the heat transfer medium flow rate T entering the primary heat exchanger 2 and the secondary heat exchanger 3 water , which can be achieved by adjusting the speed of the circulation pump or the valve opening, and reasonably distributing the recovered heat to other systems that need heating.

[0111] The following are embodiments based on the present invention. All other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0112] During the operation of the slag-discharging boiler 1, high-temperature liquid slag flows into the liquid slag collection device. Driven by the power of the liquid slag conveying pump, it enters the primary heat exchanger 2 through the liquid slag conveying pipe at a certain flow rate and velocity. Within the primary heat exchanger 2, the liquid slag undergoes intense heat exchange with the heat exchange medium, gradually decreasing its temperature while increasing the temperature of the heat exchange medium. The heated heat exchange medium then flows into the secondary heat exchanger 3. Simultaneously, external air, driven by the air blower, enters through the secondary cold air conveying pipe. It first passes through an air filter to remove impurities before entering the secondary heat exchanger 3, where it undergoes heat exchange with the heat exchange medium, raising its temperature and achieving preheating. The preheated air is distributed to the primary and secondary conveying pipes according to the boiler's combustion requirements. The hot air in the primary conveying pipe undergoes further heat exchange in the air preheater 4, where it is mixed with the hot air in the secondary conveying pipe before being delivered to the combustion area, improving combustion efficiency.

[0113] Throughout the entire process, the control system monitors the temperature, pressure, and flow parameters of various parts in real time. For example, if the temperature in the combustion area of slag discharge boiler 1 is detected to be low, indicating incomplete combustion, possibly due to insufficient air preheating temperature, the control system, based on a preset algorithm, increases the speed of the liquid slag conveying pump and the liquid slag flow rate, thereby further raising the temperature of the heat exchange medium, thereby increasing the air preheating temperature and improving combustion conditions. Conversely, when the load of slag discharge boiler 1 decreases and the combustion demand decreases, the control system correspondingly reduces the speed of the liquid slag conveying pump and the liquid slag flow rate, thereby lowering the air preheating temperature and achieving energy-saving operation. This control strategy enables the entire system to automatically adjust operating parameters according to the different operating conditions of slag discharge boiler 1, always maintaining an efficient and stable operating state, maximizing energy utilization, and reducing energy waste and environmental pollution.

[0114] Regarding system installation and commissioning: First, determine the installation locations of the various components of the primary heat exchanger 2 and the secondary heat exchanger 3 based on the layout of the slag-discharging boiler 1 and actual site conditions. A liquid slag collection device is installed below the boiler's slag outlet to ensure complete collection of the high-temperature liquid slag. The installation angle should facilitate slag outflow. The liquid slag conveying pipeline is laid according to the designed route, with attention to the pipeline slope and support structure to avoid problems such as liquid accumulation and pipeline deformation. The primary heat exchanger 2 is installed on a suitable foundation, ensuring its levelness and stability. The liquid slag inlet and outlet pipelines and the heat exchange medium inlet and outlet pipelines are connected and inspected for leaks.

[0115] The air preheater 4 is installed in a well-ventilated location, and the heat exchange medium outlet pipe of the secondary heat exchanger 2, the first delivery pipe and the second delivery pipe are connected, and a strict air tightness test is carried out.

[0116] The control system is installed with multiple temperature sensors located at the slag discharge boiler 1, the inlet and outlet of the first-stage heat exchanger 2, and the first and second inlet and outlet of the air preheater 4. Multiple pressure sensors are located on the cold air duct, the first duct, and the second duct, as well as multiple flow sensors on the liquid slag duct, the first duct, the second duct, the fifth duct, the third duct, and the fourth duct. Ensure that each sensor probe is in full contact with the measured medium and securely mounted. The data acquisition module in the control system is installed in the control cabinet, and the sensor data cables are connected. The controller in the control system is also installed in the control cabinet and programmed, entering the preset control algorithm and parameters. Actuators, such as the inverter for the liquid slag pump motor and the regulating valve for the air blower, are installed on the corresponding equipment and connected to the control circuits. After the system is installed, comprehensive commissioning is performed to check the operating status of each device, the connection of each pipeline, the accuracy of data acquisition by various sensors, and the control functions of the controller to ensure proper system operation.

[0117] In the actual operation process, when the slag discharge boiler 1 is started, the high-temperature liquid slag begins to flow into the liquid slag collection device, and the liquid slag delivery pump runs at the initially set speed to deliver the liquid slag to the first-stage heat exchanger 2. At this time, the control system begins to monitor the parameters of various parts. For example, the temperature sensor at the inlet of the first-stage heat exchanger 2 detects that the liquid slag temperature is 1500℃, the pressure sensor detects that the liquid slag delivery pressure is 0.5MPa, and the flow sensor detects that the liquid slag flow rate is 10m 3 / h. The heat exchange medium begins to absorb heat in the primary heat exchanger 2, and the temperature gradually increases.

[0118] The air enters the cold air delivery pipe in the air blower, is filtered by the air filter, and then enters the secondary heat exchanger 23. Assuming that the initial air temperature is 20°C, heat is exchanged with the heat exchange medium in the air preheater 5. The control system is set according to the initial load of the slag discharge boiler 1, and the air volume of the air blower is controlled to be 5000m 3 / h, so that the air temperature at the outlet of the air preheater 5 reaches 200°C, and then the hot air after heat exchange in the secondary heat exchanger 3 is distributed through the first delivery pipe and the second delivery pipe, and the hot air in the first delivery pipe is sent to the air preheater 5 for heat exchange again with the high-temperature flue gas sent into the air preheater 5. The hot air after heat exchange is mixed with the hot air in the second delivery pipe and then delivered to the combustion area of the slag discharge boiler 1 to ensure normal ignition and preliminary combustion of the slag discharge boiler 1.

[0119] After the slag discharge boiler 1 has been running for a period of time, the load gradually increases. For example, the temperature sensor in the combustion area of the slag discharge boiler 1 detects that the temperature begins to drop, indicating that the combustion is insufficient and more heat input is required. The controller of the control system, based on the data fed back by the temperature sensor and through the adaptive anti-interference collaborative optimization algorithm analysis, determines that the speed of the liquid slag conveying pump needs to be increased. The controller then issues a command to the inverter of the liquid slag conveying pump motor to increase the speed by 20%, increasing the liquid slag flow rate to 12m 3 As the liquid slag flow rate increases, the temperature of the heat exchange medium in the primary heat exchanger 2 further increases, thereby increasing the air preheating temperature in the air preheater 5 to 250°C, meeting the combustion requirements of the slag discharge boiler 1 when the load increases, and improving the combustion efficiency.

[0120] When the slag discharge boiler 1 is in the late stage of operation and the load gradually decreases, the control system again judges that the heat input needs to be reduced based on the data fed back by each sensor, such as the temperature increase in the combustion area of the slag discharge boiler 1 and the increase in the oxygen content of the flue gas. The controller reduces the speed of the liquid slag conveying pump, for example, by 30%, so that the liquid slag flow rate is reduced to 7m 3 / h, and reduce the air volume of the air fan to 3000m 3 / h. This reduces the air preheating temperature to 150°C, reducing unnecessary energy consumption and achieving energy-saving operation. Throughout the entire operation process, the control system continuously adjusts the operating parameters of each device based on the real-time operating conditions of the slag discharge boiler 1, ensuring that the liquid slag waste heat recovery and control system are always in optimal operating conditions. This improves the overall energy utilization efficiency of the slag discharge boiler 1 and reduces environmental pollution and energy waste.

[0121] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A waste heat recovery and control system for an anti-interference liquid slag discharge boiler, comprising an air preheater (4), characterized in that: The first inlet of the air preheater (4) is connected to the secondary heat exchanger (3) through a first conveying pipe, the secondary heat exchanger (3) is also connected to the air blower through a cold air conveying pipe, the first conveying pipe is also connected to the second conveying pipe through a three-way electromagnetic valve, the first outlet of the air preheater (4) is connected to an air mixing device (9), the second conveying pipe is also connected to the air mixing device (9), the second inlet of the air preheater (4) is connected to the exhaust pipe of the slag discharge boiler (1), the second outlet of the air preheater (4) is discharged after dust removal, the slag discharge boiler (1) is connected to the liquid slag conveying pipe through a liquid slag conveying pump, the liquid slag conveying pipe is connected to the primary heat exchanger (2), the primary heat exchanger (2) and the secondary heat exchanger (3) are connected through a third conveying pipe and a fourth conveying pipe, which are used to convey the liquid slag heat from the primary heat exchanger (2) to the secondary heat exchanger (3) for heat exchange with the cold air sent into the secondary heat exchanger (3), the third conveying pipe is provided with an electromagnetic valve a, and the fourth conveying pipe is provided with an electromagnetic valve b; A plurality of temperature sensors are respectively arranged on the inlet and outlet of the slag discharge boiler (1), the inlet and outlet of the first-stage heat exchanger (2), the first inlet and outlet of the air preheater (4), and the second inlet and outlet of the air preheater (4); A plurality of pressure sensors are respectively arranged on the cold air conveying pipe, the first conveying pipe, the liquid slag conveying pipe and the second conveying pipe; A plurality of flow sensors are respectively arranged on the liquid slag conveying pipe, the first conveying pipe, the second conveying pipe, the third conveying pipe and the fourth conveying pipe; The control system is respectively connected to a plurality of temperature sensors, a plurality of pressure sensors, a plurality of flow sensors, a liquid slag conveying pump, an air blower, a three-way solenoid valve, a solenoid valve a and a solenoid valve b, and is used to control the speed of the liquid slag conveying pump, the air volume of the air blower and the opening degree of the three-way solenoid valve, the solenoid valve a and the solenoid valve b according to a plurality of temperatures, a plurality of pressures, a plurality of flow rates and a heat load in the slag discharge boiler (1).

2. The anti-interference liquid slag discharge boiler waste heat recovery and control system according to claim 1, characterized in that: A liquid slag collecting device is further provided between the slag discharge boiler (1) and the primary heat exchanger (2). The slag discharge boiler (1) is connected to the liquid slag collecting device, and the liquid slag collecting device is connected to a liquid slag conveying pipe via a liquid slag conveying pump.

3. The anti-interference liquid slag discharge boiler waste heat recovery and control system according to claim 2, characterized in that: The liquid slag conveying pipe is a device made of multiple layers of composite thermal insulation materials, and the multiple layers of composite thermal insulation materials are ceramic fibers, rock wool and stainless steel plates from the inside to the outside.

4. The anti-interference liquid slag discharge boiler waste heat recovery and control system according to claim 1, characterized in that: The second outlet of the air preheater (5) is connected to the dust removal device (5), the induced draft fan (6), the desulfurization purification device (7) and the chimney (8) in sequence through pipelines.

5. The anti-interference liquid slag discharge boiler waste heat recovery and control system according to claim 1, characterized in that: The heat exchange medium flowing in the third conveying pipe and the fourth conveying pipe is heat transfer oil, the first-stage heat exchanger (2) is a spiral heat exchanger, the heat exchange medium is inside the tube of the spiral heat exchanger, and a spiral device for continuously turning and conveying the liquid slag is provided outside the tube of the spiral heat exchanger.

6. The control method for the waste heat recovery and control system of the anti-interference liquid slag discharge boiler according to claim 1, characterized in that: The steps include: The liquid slag discharged from the slag discharge boiler (1) is fed into the primary heat exchanger (2) through the liquid slag conveying pipe and the liquid slag conveying pump to realize heat exchange between the liquid slag and the heat exchange medium. The heat exchange medium after absorbing heat exchanges heat with the cold air fed into the secondary heat exchanger (3) in the secondary heat exchanger (3); A portion of the heated hot air enters the air preheater (4) through the first delivery pipe, and exchanges heat with the boiler flue gas sent into the air preheater (4) from the slag discharge boiler (1) in the air preheater (4). The reheated air is mixed with the other portion of the heated hot air in the air mixing device (9). The mixed hot air is sent to the slag discharge boiler (1) for reuse. The boiler flue gas after heat exchange is discharged after dust removal. The control system regulates the liquid slag conveying pump speed, the fan air volume, the openings of the three-way solenoid valve, the solenoid valve a and the solenoid valve b according to the temperature measurement values of each temperature sensor, the pressure measurement values of each pressure sensor and the flow measurement values of each flow sensor received in real time and the heat load in the slag discharge boiler (1), so as to keep the system in an optimal operating state at all times.

7. The control method for the waste heat recovery and control system of the anti-interference liquid slag discharge boiler according to claim 6, characterized in that: The control system regulates the liquid slag conveying pump speed, the fan air volume, the opening of the three-way solenoid valve, the solenoid valve a and the solenoid valve b according to the temperature measurement values of each temperature sensor, the pressure measurement values of each pressure sensor and the flow measurement values of each flow sensor received in real time and the heat load in the slag discharge boiler (1), so that the system is always in the best operating state: According to the deviation between the set value and the measured value of each parameter, the speed of the liquid slag conveying pump, the air volume of the fan, the opening of the three-way solenoid valve, solenoid valve a and solenoid valve b are adjusted proportionally. The steady-state error is eliminated by integral adjustment of the deviation to ensure that the parameter is finally stabilized at the set value. The early action is achieved by differential adjustment of the deviation change rate.

8. The control method for the waste heat recovery and control system of the anti-interference liquid slag discharge boiler according to claim 7, characterized in that: When adjusting the liquid slag conveying pump speed, fan air volume, three-way solenoid valve, solenoid valve a and solenoid valve b opening: According to the cold air temperature of the air preheater, the temperature of the air heated by the air preheater, the constant pressure specific heat capacity of the air and the air flow rate, the heat balance equation of the air preheating unit is established to obtain the heat absorbed by the air; Based on the initial temperature of the liquid slag discharged from the slag discharge boiler, the outlet temperature of the liquid slag after waste heat recovery, the constant pressure specific heat capacity of the liquid slag and the liquid slag flow rate, the heat balance equation of the liquid slag waste heat recovery system is established to obtain the heat released by the liquid slag; Establish an energy conservation equation. Based on the heat absorbed by the air, the heat released by the liquid slag, and the heat loss of the boiler itself, the sum of the effective heat removed by the steam or hot water generated by the boiler is equal to the total heat input by the boiler fuel combustion. With the goal of improving the overall thermal efficiency of the boiler, reducing fuel consumption, and meeting the system operation constraints, efficient energy utilization is achieved by maximizing the total thermal efficiency of the boiler. The temperature setting value and flow setting value are determined based on the heat absorbed by the air and the heat released by the liquid slag corresponding to the maximum overall thermal efficiency of the boiler.

9. The control method for the waste heat recovery and control system of the anti-interference liquid slag discharge boiler according to claim 8, characterized in that: The constraints are as follows: T air,out,min ≤T air,out ≤T air,out,max ; T slag,out,min ≤T slag,out ≤T slag,out,max ; T smoke,out ≥T dewpoint +ΔT; F air,min ≤F air ≤F air,max ; F slag,min ≤F slag ≤F slag,max ; Where T air，out，max The maximum temperature of the air after being heated by the air preheater; T air,out The temperature of the air after being heated by the air preheater; T air,out,min The lowest temperature of the air after being heated by the air preheater, T slag，out，max is the maximum temperature of liquid slag outlet after waste heat recovery, T slag，out，min is the lowest temperature of liquid slag outlet after waste heat recovery, T slag,out T is the outlet temperature of liquid slag after waste heat recovery; smoke,out is the flue gas temperature after passing through the air preheater, T dewpoint is the flue gas dew point temperature after passing through the air preheater, ΔT is the set temperature margin, F air，max is the maximum air flow rate, F air is the air flow rate; F air，min is the minimum air flow rate, F slag，max is the maximum flow rate of liquid slag, F slag，min is the minimum flow rate of liquid slag; F slag is the liquid slag flow rate.

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