Self-adaptive liquid deslagging boiler system and method based on waste heat utilization

Abstract

The invention relates to a self-adaptive liquid deslagging boiler system and method based on waste heat utilization, air sent out by a dry heat exchanger tube pass in the system can reach a higher temperature, high-temperature liquid slag waste heat is fully recycled and exchanges heat with fed cold air in a shell-and-tube heat exchanger again, so that the cold air is heated, and the heat exchange efficiency is improved. High-temperature flue gas discharged by the deslagging boiler exchanges heat with fed cold air to heat the cold air, that is, the cold air obtains different-grade waste heat of the high-temperature flue gas and high-temperature liquid slag in the air preheater and the shell-and-tube heat exchanger respectively, and split-flow gradient utilization of energy is achieved. And the two kinds of heated cold air are mixed in the first-stage mixing device and conveyed into the deslagging boiler through the hot air conveying pipe, so that the combustion condition of the deslagging boiler is improved. The rotating speed of the smoke exhaust fan and the opening degrees of the three-way electromagnetic valve a, the three-way electromagnetic valve b and the three-way electromagnetic valve c are regulated and controlled in real time according to the thermal load requirement of the deslagging boiler, heat quality reduction and waste heat waste are reduced, and the overall performance of the boiler is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of boilers, and in particular relates to a self-adaptive liquid slagging boiler system and method based on waste heat utilization. Background Art

[0002] Liquid slagging boilers are boilers in which the slag generated by fuel combustion is melted into a liquid form at high temperatures within the slag chamber and discharged from the furnace. Liquid slagging boilers are widely used in the power industry, but their ash waste heat recovery and air preheating technologies still face challenges. Traditional methods for recovering waste heat from ash in liquid slagging boilers typically use water quenching, which not only wastes water resources but also produces pollutants. Furthermore, conventional air preheaters are inefficient in recovering flue gas heat, failing to meet energy conservation and environmental protection requirements.

[0003] Furthermore, the previous waste heat recovery system failed to fully utilize the heat from the liquid slag, resulting in significant energy waste. Furthermore, the system lacked close coordination with the air preheating unit, making it difficult for the air preheating temperature to meet the boiler's requirements for efficient combustion, further impacting overall boiler performance. 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 an adaptive liquid slag discharge boiler system and method based on waste heat utilization, so as to achieve efficient recovery and full utilization of liquid slag waste heat, optimize the air preheating process, improve the overall energy utilization efficiency of the boiler, and ensure stable and reliable operation of the system.

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

[0006] The present invention provides an adaptive liquid slag discharge boiler system based on waste heat utilization, including an air preheater, a first outlet of the air preheater is connected to a primary mixer, a first inlet of the air preheater is connected to a cold air conveyor through a first conveying pipe, the first conveying pipe is further connected to a second conveying pipe through a three-way solenoid valve a, the second conveying pipe is used to convey part of the cold air to a shell and tube heat exchanger for heat exchange, and after the cold air is heated by heat exchange, a part of it passes through the three-way solenoid valve c and enters the primary mixing device through the fifth conveying pipe, while the other part passes through the three-way solenoid valve c and is discharged to the outside through the sixth conveying pipe; The slag boiler is connected to an exhaust pipe via a flue gas fan. The exhaust pipe is connected to the second inlet of the air preheater for heat exchange with the cold air entering the air preheater via the first delivery pipe. The second outlet of the air preheater is connected to the third delivery pipe and the fourth delivery pipe respectively via a three-way solenoid valve b. The third delivery pipe is used to deliver part of the flue gas to the dry heat exchanger for heat exchange with the liquid slag. The flue gas after heat exchange in the dry heat exchanger enters the shell and tube heat exchanger for heat exchange. The flue gas delivered by the fourth delivery pipe is mixed with the flue gas after heat exchange in the shell and tube heat exchanger in the secondary mixer and then discharged after dust removal.

[0007] Multiple temperature sensors are installed at the inlet and outlet of the slagging boiler, dry heat exchanger, shell and tube heat exchanger, and air preheater;

[0008] A plurality of flow sensors are respectively arranged on the first delivery pipe, the second delivery pipe, the third delivery pipe, the fourth delivery pipe, the fifth delivery pipe, the sixth delivery pipe and the smoke exhaust pipe;

[0009] The control system is respectively connected to the smoke exhaust fan, each temperature sensor, each flow sensor, three-way solenoid valve a, three-way solenoid valve b and three-way solenoid valve c, and is used to control the speed of the smoke exhaust fan and the opening of the three-way solenoid valve a, three-way solenoid valve b and three-way solenoid valve c according to the heat load in the slag discharge boiler.

[0010] The temperature sensor in the control system uses a thermocouple sensor, which has the characteristics of high precision and fast response, and can accurately measure temperature changes in high-temperature environments. The flow sensor uses an electromagnetic flowmeter to accurately measure the boiler exhaust and air flow.

[0011] The control system consists of a data collector, a controller, and an actuator. The data collector uses a high-speed data acquisition card to quickly collect sensor data and transmit it to the controller. The controller, a programmable logic controller, uses a proportional-integral-differential algorithm to analyze and process the collected data, and the actuator adjusts the equipment's operating parameters.

[0012] Preferably, the shell side of the dry heat exchanger is connected to the slag discharge boiler via a liquid slag discharge cooling crusher. The outlet of the liquid slag discharge cooling crusher is also provided with a temperature sensor, which is also connected to the control system. The liquid slag discharge cooling crusher uses a special cooling structure and crushing tool to cool the liquid slag and crush it into small particles, thereby increasing the contact area with the heat exchanger and improving the heat exchange capacity of the medium.

[0013] Preferably, an air filter is connected to the outlet of the cold air conveyor. The filtration accuracy of the air filter can reach 5mm. The air filter can remove dust and impurities in the air to prevent dust from accumulating in the shell and tube heat exchanger and affecting waste heat recovery. A muffler can be provided on the air inlet pipe of the cold air conveyor to reduce noise when air enters.

[0014] Preferably, the heat exchange tubes of the shell and tube heat exchanger are stainless steel tubes, and a plurality of baffles are provided in the shell side of the shell and tube heat exchanger to enhance the heat exchange effect between boiler exhaust gas and cold air.

[0015] Preferably, the shell side of the shell and tube heat exchanger and the fourth delivery pipe are both connected to a secondary mixing device, and the secondary mixing device is connected to the discharge unit through a pipeline.

[0016] Preferably, the emission unit includes a dust collector, an induced draft fan, a desulfurization device and a chimney, the dust collector is connected to the induced draft fan through a pipeline, the induced draft fan is connected to a three-stage mixing device through a pipeline, the three-stage mixing device is connected to the desulfurization device through a pipeline, the desulfurization device is connected to the chimney through a pipeline, and the sixth conveying pipe is also connected to the three-stage mixing device.

[0017] Preferably, the liquid slag cooling crusher includes a crushing chamber with a cooling jacket and crushing tools made of a high-temperature resistant alloy. The cooling jacket of the liquid slag cooling crusher utilizes circulating water cooling, with the cooling water flow rate adjustable based on the liquid slag temperature and flow rate, ensuring rapid cooling while crushing the liquid slag. The high-temperature resistant alloy of the crushing tools offers excellent wear resistance and high-temperature strength, effectively crushing the high-temperature liquid slag into uniform small particles with a diameter of 5 mm to 20 mm.

[0018] The present invention provides a method for an adaptive liquid slag discharge boiler system based on waste heat utilization, comprising the following steps:

[0019] A portion of the cold air conveyed by the cold air conveyor is sent into the air preheater through the first conveying pipe, and exchanges heat with the flue gas sent into the air preheater by the slag discharge boiler. After the heat exchange, the cold air becomes hot air a. A portion of the flue gas after heat exchange is sent into the dry heat exchanger through the third conveying pipe, and exchanges heat with the high-temperature liquid slag sent into the dry heat exchanger by the slag discharge boiler through air quenching.

[0020] The flue gas after air quenching and heat exchange is sent into the shell side of the shell and tube heat exchanger, and exchanges heat with another portion of cold air sent into the tube side of the shell and tube heat exchanger through the second delivery pipe by the cold air conveyor. After the heat exchange, the cold air becomes hot air b; a portion of the hot air b is mixed with the hot air a at the first mixing device through the fifth delivery pipe, and after mixing, it is sent to the slag discharge boiler for reuse through the hot air delivery pipe. The other portion of the hot air b is mixed with the treated flue gas discharged from the shell side of the shell and tube heat exchanger through the sixth delivery pipe and is then discharged;

[0021] The control system will receive flow measurement value signals from the first conveying pipe, the second conveying pipe, the third conveying pipe, the fourth conveying pipe, the fifth conveying pipe, the sixth conveying pipe and the smoke exhaust pipe, as well as temperature measurement value signals from the inlet and outlet of the slag discharge boiler, the dry heat exchanger, the inlet and outlet of the shell and tube heat exchanger, and the inlet and outlet of the air preheater. By calculating the deviation between each temperature setting value and each temperature measurement value and the deviation between each flow setting value and each flow measurement value, the control system will regulate the opening of the three-way solenoid valve a, the three-way solenoid valve b, and the three-way solenoid valve c and the speed of the smoke exhaust fan according to the load demand of the slag discharge boiler combustion, so as to adjust the temperature of the air sent into the slag discharge boiler when the load of the slag discharge boiler changes.

[0022] The 1300℃~1600℃ liquid slag produced by the slag discharge boiler flows into the liquid slag inlet of the dry heat exchanger through the slag discharge port, is cooled to 100℃~200℃ in the dry heat exchanger, and is discharged from the slag discharge port for subsequent processing and utilization.

[0023] After heat exchange with air in the air preheater, the boiler exhaust flue gas temperature drops. The exhaust gas volume Q6 entering the dry heat exchanger is determined based on the residual heat of the liquid slag. After fully absorbing the residual heat from the liquid slag, the boiler exhaust flue gas enters the shell-and-tube heat exchanger 4 for heat exchange with the air. After absorbing the heat, the air temperature rises, while the boiler exhaust flue gas temperature drops. The cold air receives different levels of residual heat from the boiler liquid slag and exhaust gas in the air preheater and shell-and-tube heat exchanger, respectively, achieving cascaded energy utilization. The exhaust gas flow rate and air flow rate along different pipelines are determined based on the residual heat of the boiler slag and exhaust gas. Q1 = Q3 + Q8, Q2 = Q3 + Q4, Q5 = Q6 + Q7, and Q4 = Q8 + Q9. The preheated air is distributed through the pipeline to the combustion area of the liquid slag boiler at the set flow rate, improving combustion efficiency. The control system monitors parameters such as temperature and flow in real time throughout the entire process. It automatically adjusts the openings of three-way solenoid valves a, b, and c, as well as the exhaust fan speed, based on boiler load changes and combustion conditions. Air preheated in the shell-and-tube heat exchanger and the air preheater simultaneously enter the air preheater. This hot air is then introduced into the front of the slagging boiler for preheating and conveying the pulverized coal.

[0024] Coordinated regulation of waste heat recovery from dry heat exchangers and air preheating achieves optimal heat distribution and utilization, improving the thermal efficiency and operational stability of the entire boiler system. Specifically, while meeting the required air temperature for boiler combustion, it maximizes waste heat recovery from the liquid slag, minimizing energy waste and fuel consumption while ensuring system operational stability and safety.

[0025] In dry heat exchanger waste heat recovery, the heat from the liquid slag is transferred to the cooling medium in the dry heat exchanger. The heat transfer process between dry heat exchanger waste heat recovery and air preheating waste heat recovery is influenced by multiple factors. The first is the load of the slagging boiler. Changes in the slagging boiler load can lead to changes in the amount and temperature of liquid slag generated, the flue gas flow rate and temperature, and the air flow rate. For example, during high-load operation, liquid slag generation increases and its temperature rises, while flue gas flow rate and temperature also increase, necessitating corresponding adjustments to the operating parameters of the dry heat exchanger waste heat recovery and air preheating waste heat recovery. The second factor is the medium flow rate and temperature. For example, in dry heat exchanger waste heat recovery, the flow rate and inlet temperature of the cooling medium affect the liquid slag heat recovery efficiency, while in air preheating waste heat recovery, the air flow rate and inlet temperature also affect the air preheating effect.

[0026] Preferably, the high-temperature liquid slag fed from the slagging boiler into the dry heat exchanger is crushed and cooled by a liquid slagging crusher.

[0027] Preferably, the differences between the temperatures and the flows are calculated using a proportional-differential-integral method, which comprises the following steps:

[0028] The temperature difference and the flow difference are calculated based on the measured values of temperature and flow obtained at the same time and the set values of temperature and flow;

[0029] The currently obtained temperature difference or flow difference is compared with the positive and negative values using the proportional operation method to obtain a temperature control signal or a flow size control signal;

[0030] The currently obtained temperature difference or flow difference is differentiated using a differential operation method to obtain a temperature change rate signal or a flow change rate signal;

[0031] The currently obtained temperature difference or flow difference is integrated using an integration operation method to obtain a temperature cumulative deviation signal or a flow cumulative deviation signal;

[0032] The signals obtained according to the above-mentioned proportional operation method, differential operation method and integral operation method are used to control the speed of the smoke exhaust fan and the opening of the three-way solenoid valve a, three-way solenoid valve b and three-way solenoid valve c.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention utilizes the coordinated operation of dry-type waste heat recovery from liquid slag and air preheating to achieve a high temperature for the air discharged from the dry heat exchanger tubes. The high-temperature liquid slag waste heat is fully recovered and exchanged again with incoming cold air in the shell-and-tube heat exchanger, heating the cold air. The high-temperature flue gas discharged from the slag discharge boiler is heated in the air preheater along with the incoming cold air, thereby heating the cold air. This means that the cold air receives different levels of waste heat from the high-temperature flue gas and the high-temperature liquid slag in the air preheater and the shell-and-tube heat exchanger, respectively, achieving cascaded energy utilization. Furthermore, the two heated cold air streams are mixed in a primary mixing device and delivered to the slag discharge boiler via a hot air delivery pipe, improving combustion conditions in the slag discharge boiler. The heat content of the hot air delivered in the hot air delivery pipe is achieved by real-time regulation of the exhaust fan speed and the openings of three-way solenoid valves a, b, and c, based on the heat load requirements of the slag discharge boiler. This minimizes heat quality degradation and waste heat, thereby improving overall boiler performance.

[0035] This invention utilizes temperature sensors, flow sensors, and a control system to monitor fluctuations in fuel quality and environmental disturbances during the operation of the slagging boiler in real time. Through an adaptive proportional-integral-differential control algorithm, the system automatically adjusts control parameters to quickly adapt to varying load conditions, maintaining stable boiler operation and ensuring unimpeded slagging and waste heat utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of an adaptive liquid slag discharge boiler system based on waste heat utilization provided by the present invention.

[0037] Figure 2 This is a flow chart of the adaptive proportional-integral-differential algorithm control system provided by the present invention.

[0038] Reference numerals

[0039] 1. Slag discharge boiler; 2. Liquid slag cooling crusher; 3. Dry heat exchanger; 4. Shell and tube heat exchanger; 5. Air preheater; 6. Primary mixing device; 7. Secondary mixing device; 8. Dust collector; 9. Induced draft fan; 10. Third-stage mixing device; 11. Desulfurization device; 12. Chimney.

[0040] Q1, total hot air flow; Q2, total cold air flow; Q3, cold air flow entering the air preheater; Q4, cold air flow entering the tubular heat exchanger; Q5, boiler exhaust volume; Q6, exhaust volume entering the dry cooling heat exchanger; Q7, exhaust volume entering the secondary mixing device; Q8, hot air flow entering the primary mixing device; Q9, hot air flow entering the tertiary mixing device. DETAILED DESCRIPTION

[0041] 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.

[0042] The inventors have discovered that liquid slag boilers have many problems in terms of ash waste heat recovery and utilization, poor air preheating synergy, and lack of a stable control system, making them unable to meet the requirements for efficient and stable boiler operation. This patent constructs an adaptive liquid slag boiler system based on waste heat cascade utilization, which includes a waste heat recovery unit, an air preheating unit, and a control system. Through the collaborative work of each unit, efficient recovery and utilization of the waste heat of the liquid slag boiler and improvement of boiler operation stability are achieved. An adaptive proportional-integral-differential algorithm is introduced into the control system. The algorithm receives the measured values from each temperature sensor and flow sensor, calculates the deviation from the set value, and compares the measured value deviation with the set value deviation. In this way, the solenoid valve opening is adjusted to achieve precise control of the system operating parameters, and then flexibly adjusts according to the actual operating conditions of the boiler to achieve precise utilization of the energy based on the diversion cascade and stability of the anti-interference operation, thereby optimizing the waste heat recovery of high-temperature liquid slag in traditional boilers and the problem of boiler operation stability.

[0043] In view of this, the present invention provides an adaptive liquid slag discharge boiler system and method based on waste heat utilization. The present invention can intelligently adjust the operating parameters according to the boiler load conditions, effectively improve the liquid slag waste heat recovery efficiency and air preheating effect, and improve the energy utilization rate and operating stability of the liquid slag discharge boiler, with significant economic and environmental benefits.

[0044] like Figures 1 and 2 As shown, the present invention provides an adaptive liquid slag discharge boiler system based on waste heat utilization, including an air preheater 5, a first outlet of the air preheater 5 is connected to a primary mixer 6, a first inlet of the air preheater 5 is connected to a cold air conveyor through a first conveying pipe, the first conveying pipe is further connected to a second conveying pipe through a three-way solenoid valve a, the second conveying pipe is used to convey part of the cold air to the shell and tube heat exchanger 4 for heat exchange, and after the heat exchange and temperature increase, a part of the cold air passes through the three-way solenoid valve c and enters the primary mixing device 6 through the fifth conveying pipe, while the other part passes through the three-way solenoid valve c and is discharged to the outside through the sixth conveying pipe; The slag discharge boiler 1 is connected to the exhaust pipe through a flue gas fan. The exhaust pipe is connected to the second inlet of the air preheater 5 and is used to exchange heat with the cold air entering the air preheater 5 through the first conveying pipe. The second outlet of the air preheater 5 is connected to the third conveying pipe and the fourth conveying pipe respectively through a three-way solenoid valve b. The third conveying pipe is used to convey part of the flue gas to the dry heat exchanger 3 for heat exchange with the liquid slag. The flue gas after heat exchange in the dry heat exchanger 3 enters the shell and tube heat exchanger 4 for heat exchange. The flue gas conveyed by the fourth conveying pipe is mixed with the flue gas after heat exchange in the shell and tube heat exchanger 4 in the secondary mixer 7 and discharged after dust removal.

[0045] Multiple temperature sensors are respectively installed at the inlet and outlet of the slag discharge boiler 1, the dry heat exchanger 3, the inlet and outlet of the shell and tube heat exchanger 4, and the inlet and outlet of the air preheater 5;

[0046] A plurality of flow sensors are respectively arranged on the first delivery pipe, the second delivery pipe, the third delivery pipe, the fourth delivery pipe, the fifth delivery pipe, the sixth delivery pipe and the smoke exhaust pipe;

[0047] The control system is respectively connected to the smoke exhaust fan, each temperature sensor, each flow sensor, three-way solenoid valve a, three-way solenoid valve b and three-way solenoid valve c, and is used to control the smoke exhaust fan speed and the opening of the three-way solenoid valve a, three-way solenoid valve b and three-way solenoid valve c according to the heat load in the slag discharge boiler 1.

[0048] The dry heat exchanger 3 and air preheater 5 provided in this invention coordinate and control each other to achieve optimal heat distribution and utilization, improving the thermal efficiency and operational stability of the entire slag discharge boiler 1. Specifically, while meeting the air temperature required for combustion in the slag discharge boiler 1, the system maximizes the recovery of waste heat from the high-temperature liquid slag, reduces energy waste and fuel consumption, and ensures the stability and safety of system operation.

[0049] The control system uses thermocouples as temperature sensors, offering high precision and fast response, capable of accurately measuring temperature changes in high-temperature environments. The flow sensor uses an electromagnetic flowmeter, accurately measuring boiler exhaust and air flow. The data acquisition device uses a high-speed data acquisition card, rapidly collecting sensor data and transmitting it to the controller. The controller, a programmable logic controller, utilizes a proportional-integral-differential algorithm to analyze and process the collected data, and uses actuators to adjust equipment operating parameters.

[0050] The heat transfer process between the dry heat exchanger 3 and the air preheater 5 is affected by multiple factors. The first is the load of the slagging boiler 1. Changes in the load of the slagging boiler 1 will cause changes in the amount and temperature of high-temperature liquid slag, the flue gas flow rate and temperature, and the air flow rate.

[0051] For example, when the slag-draining boiler 1 operates at high load, the amount of high-temperature generated increases, the temperature rises, and the flue gas flow rate and temperature also increase, requiring corresponding adjustments to the operating parameters of the waste heat recovery unit and the air preheating unit. Secondly, the medium flow rate and temperature. For example, the flow rate and inlet temperature of the cooling medium in the dry heat exchanger 3 affect the liquid slag heat recovery efficiency, while the air flow rate and inlet temperature in the air preheater 5 also affect the air preheating effect.

[0052] In the process of coordinated operation, it is necessary to establish an energy balance mechanism to ensure that the heat recovered from the dry heat exchanger and the air preheating waste heat can be reasonably utilized. The energy balance equation can be established to calculate the energy income and expenditure of the entire system. For example, the heat Q recovered from the dry heat exchanger is slag And the heat Q recovered from the waste heat of air preheating airThe sum should be equal to the total waste heat of the liquid slag and flue gas discharged from the boiler minus the heat loss of the system Q loss , that is, Q slag +Q air =Q total-slag-smoke -Q loss By monitoring and calculating the heat of each part, the operating parameters of the two subsystems are reasonably adjusted to achieve optimal energy utilization. Then, based on the recovered heat, the exhaust flow rate and air flow rate are determined, for example, Q1 = Q3 + Q8, Q2 = Q3 + Q4, Q5 = Q6 + Q7, and Q4 = Q8 + Q9.

[0053] Operational Stability Balancing Mechanism: To ensure system operational stability, it is necessary to consider the coordinated operation of dry heat exchanger waste heat recovery and air preheating waste heat recovery under different operating conditions. During startup, shutdown, or sudden load changes in the deslagging boiler, the operating parameters of the dry heat exchanger waste heat recovery and air preheating waste heat recovery systems may change dramatically. In these cases, special control strategies are required to maintain system stability. For example, during the deslagging boiler startup phase, air preheating waste heat recovery can be activated first to gradually increase the temperature of the air entering the deslagging boiler, creating conditions for stable combustion. Simultaneously, dry heat exchanger waste heat recovery can be gradually activated, and the cooling medium flow rate can be adjusted based on the generation and temperature of high-temperature liquid slag. In the event of sudden load changes, the parameters of the dry heat exchanger waste heat recovery and air preheating waste heat recovery systems can be quickly adjusted to enable them to quickly adapt to the new operating conditions, avoiding system failures or significant efficiency drops.

[0054] The specific method of coordinated operation involves adjusting the heat exchange between the dry heat exchanger's waste heat recovery and the air preheating waste heat recovery based on the liquid slag temperature and flow rate, as well as the air temperature required for combustion in the slag discharge boiler. For example, if the liquid slag temperature is high, the heat recovery capacity of the dry heat exchanger's waste heat recovery can be appropriately increased, while ensuring that the air preheating temperature meets combustion requirements. This can be achieved by adjusting the coolant flow rate in the dry heat exchanger, lowering the coolant inlet temperature, or increasing the heat exchange area. Furthermore, for air preheating waste heat recovery, the flue gas-air heat exchange rate can be controlled by adjusting the opening of the flue gas damper to maintain a stable air preheating temperature.

[0055] For flow regulation, the distribution of liquid slag flow and air flow is coordinated based on the load of the deslagging boiler. During low-load operation, the amount of liquid slag generated decreases. In this case, the cooling medium flow in the dry heat exchanger can be appropriately reduced. At the same time, the ratio of air flow to flue gas flow can be fine-tuned based on the required air preheat temperature. For example, the air flow can be controlled by adjusting the fan speed, or the flue gas flow can be controlled by adjusting the valve in the flue.

[0056] The heat recovered by dry heat exchangers and air preheaters can be used in a comprehensive manner. For example, heat recovered by dry heat exchangers can be used to preheat boiler feed water or heat other processes requiring heat energy. When operating in tandem, energy balance should be achieved based on the heat requirements and priorities of each process.

[0057] An advanced control system is used to establish a dynamic mathematical model of the dry heat exchanger and air preheater. Based on current operating parameters such as liquid slag temperature, air temperature, flow rate, and target parameters (such as expected air preheating temperature, liquid slag outlet temperature, etc.), the system operating status is predicted and the optimal adaptive control strategy is calculated.

[0058] Specifically, the adaptive proportional-integral-differential algorithm is as follows: according to the deviation between the set value and the measured value of the temperature, flow rate, and enthalpy value; the proportional regulation proportionally adjusts the opening of the three-way solenoid valve a, three-way solenoid valve b, and three-way solenoid valve c according to the deviation of the temperature, flow rate, and enthalpy value parameters, and sends it to the three-way solenoid valve a, three-way solenoid valve b, and three-way solenoid valve c; the integral regulation integrates the deviation to eliminate the steady-state error, ensuring that the temperature, flow rate, and enthalpy value are finally stabilized at the set value; the differential regulation acts in advance according to the deviation change rate, suppresses the drastic fluctuation of the parameters, enhances the system stability, and achieves the stability of the boiler operation.

[0059] Specifically, the shell side of the dry heat exchanger 3 is connected to the slag discharge boiler 1 via a liquid slag discharge cooling crusher 2 , and a temperature sensor is also provided at the outlet of the liquid slag discharge cooling crusher 2 , which is also connected to the control system.

[0060] The liquid slag cooling crusher 2 includes a crushing chamber and a crushing tool. The crushing chamber is provided with a cooling jacket, and the crushing tool is made of a high-temperature resistant alloy material.

[0061] The liquid slag crusher 2 adopts a special cooling structure and crushing tools, which can crush the liquid slag into small particles while cooling it, thereby increasing the contact area with the heat exchanger and improving the heat exchange capacity of the medium.

[0062] The cooling jacket of the liquid slag crusher 2 utilizes circulating water cooling, with the cooling water flow rate adjusted according to the liquid slag temperature and flow rate, ensuring rapid cooling while crushing the liquid slag. The high-temperature alloy material of the crushing tool has excellent wear resistance and high-temperature strength, effectively crushing the high-temperature liquid slag into uniform small particles with a particle size of 5mm to 20mm.

[0063] The boiler 1 generates high-temperature liquid slag at 1300°C to 1600°C, which flows through the slag discharge port into the liquid slag crusher 2 for crushing and cooling, and then is sent to the dry heat exchanger 3, where it is cooled to 100°C to 200°C and discharged from the slag discharge port of the dry heat exchanger 3 for subsequent processing and utilization.

[0064] Specifically, the outlet of the cold air conveyor is connected to an air filter, and the filtration accuracy of the air filter can reach 5mm, effectively removing impurities in the air.

[0065] Specifically, the heat exchange tubes of the shell and tube heat exchanger 4 are stainless steel tubes, and a plurality of baffles are provided in the shell side of the shell and tube heat exchanger 4 to enhance the heat exchange effect between the boiler exhaust gas and the cold air.

[0066] Specifically, the shell side and the fourth delivery pipe of the shell and tube heat exchanger 4 are both connected to the secondary mixing device 7 , and the secondary mixing device 7 is connected to the discharge unit through a pipeline.

[0067] Specifically, the emission unit includes a dust collector 8, an induced draft fan 9, a desulfurization device 11 and a chimney 12. The dust collector 8 is connected to the induced draft fan 9 through a pipeline. The induced draft fan 9 is connected to a three-stage mixing device 10 through a pipeline. The three-stage mixing device 10 is connected to the desulfurization device 11 through a pipeline. The desulfurization device 11 is connected to the chimney 12 through a pipeline. The sixth conveying pipe is also connected to the three-stage mixing device 10.

[0068] An adaptive liquid slag discharge boiler method based on waste heat utilization includes the following steps:

[0069] A portion of the cold air conveyed by the cold air conveyor is sent into the air preheater 5 through the first conveying pipe, and exchanges heat with the flue gas sent into the air preheater 5 by the slag discharge boiler 1. After the heat exchange, the cold air becomes hot air a. A portion of the flue gas after heat exchange is sent into the dry heat exchanger 3 through the third conveying pipe, and exchanges heat with the high-temperature liquid slag sent into the dry heat exchanger 3 by the slag discharge boiler 1 through air quenching.

[0070] The flue gas after air quenching and heat exchange is sent into the shell side of the shell and tube heat exchanger 4, and exchanges heat with another portion of cold air sent into the tube side of the shell and tube heat exchanger 4 through the second delivery pipe by the cold air conveyor. After the heat exchange, the cold air becomes hot air b. A portion of the hot air b is mixed with the hot air a at the first mixing device 6 through the fifth delivery pipe. After mixing, it is sent to the slag discharge boiler 1 for reuse through the hot air delivery pipe. The other portion of the hot air b is mixed with the treated flue gas discharged from the shell side of the shell and tube heat exchanger 4 through the sixth delivery pipe and is then discharged.

[0071] The control system will receive flow measurement value signals from the first conveying pipe, the second conveying pipe, the third conveying pipe, the fourth conveying pipe, the fifth conveying pipe, the sixth conveying pipe and the smoke exhaust pipe, as well as temperature measurement value signals from the inlet and outlet of the slag discharge boiler 1, the dry heat exchanger 3, the inlet and outlet of the shell and tube heat exchanger 4, and the inlet and outlet of the air preheater 5. By calculating the deviation between each temperature setting value and each temperature measurement value and the deviation between each flow setting value and each flow measurement value, the control system will regulate the opening of the three-way solenoid valve a, the three-way solenoid valve b, and the three-way solenoid valve c and the speed of the smoke exhaust fan according to the load demand of the combustion of the slag discharge boiler 1, so as to adjust the temperature of the air fed into the slag discharge boiler 1 when the load of the slag discharge boiler 1 changes.

[0072] Specifically, the high-temperature liquid slag fed into the dry heat exchanger 3 by the slagging boiler 1 is crushed and cooled by the liquid slag crusher 2 .

[0073] Specifically, the differences between the temperatures and the flow rates are calculated using a proportional-differential-integral method, which includes the following steps:

[0074] The temperature difference and the flow difference are calculated based on the measured values of temperature and flow obtained at the same time and the set values of temperature and flow;

[0075] The currently obtained temperature difference or flow difference is compared with the positive and negative values using the proportional operation method to obtain a temperature control signal or a flow size control signal;

[0076] The currently obtained temperature difference or flow difference is differentiated using a differential operation method to obtain a temperature change rate signal or a flow change rate signal;

[0077] The currently obtained temperature difference or flow difference is integrated using an integration operation method to obtain a temperature cumulative deviation signal or a flow cumulative deviation signal;

[0078] The signals obtained according to the above-mentioned proportional operation method, differential operation method and integral operation method are used to control the speed of the smoke exhaust fan and the opening of the three-way solenoid valve a, three-way solenoid valve b and three-way solenoid valve c.

[0079] The cold air can obtain different grades of waste heat from boiler liquid slag and exhaust gas in the air preheater 5 and the shell and tube heat exchanger 4 respectively, thereby realizing the graded utilization of energy.

[0080] Specifically, the high-temperature liquid slag fed from the boiler 1 into the dry heat exchanger 3 needs to be crushed and cooled by the liquid slag cooling crusher 2 . Specific embodiments

[0082] Liquid slag at 1300°C to 1600°C produced by the slag discharge boiler 1 flows through the slag discharge port into the liquid slag cooling and crushing device 2. Inside the cooling jacket of the liquid slag cooling and crushing device 2, the high-temperature liquid slag rapidly cools and is simultaneously broken into small particles by crushing tools. The crushed, high-temperature liquid slag is then fed into the dry heat exchanger 3 for heat exchange with the boiler exhaust gas. The boiler exhaust gas absorbs the heat from the liquid slag, raising its temperature. Driven by the induced draft fan 9, it flows into the shell side of the shell-and-tube heat exchanger 4. The outside air, driven by the air fan, enters the tube side of the shell-and-tube heat exchanger 4 through the air inlet duct. After heat exchange, the cold air temperature rises, achieving preheating.

[0083] The flue gas from the shell side of shell-and-tube heat exchanger 4 and some of the hot air from the tube side of the shell-and-tube heat exchanger 4 enter dust collector 8 for dust removal. The hot air then flows through a flow control device and enters the flue gas mixing device. The hot air passes through the flue gas mixing device and enters the flue duct between desulfurization equipment 11 and chimney 12. The hot air mixes with the clean flue gas, raising its temperature before being discharged through chimney 12.

[0084] Preheated air is precisely distributed to the combustion area according to the combustion requirements of the slag discharge boiler 1, improving combustion efficiency. Throughout the entire process, the control system monitors the inlet and outlet temperatures of the slag discharge boiler 1, the dry heat exchanger 3 at various locations, the inlet and outlet temperatures of the shell-and-tube heat exchanger 4, and the inlet and outlet temperatures of the air preheater 5. It also monitors the flow parameters of the first, second, third, fourth, fifth, and sixth delivery pipes, as well as the exhaust pipe. An adaptive proportional-integral-differential algorithm is used to calculate the deviations between measured temperature values and between set flow values. By comparing the deviations between measured values and set flow values, the openings of three-way solenoid valves a, b, and c, as well as the exhaust fan speed, are controlled. This adaptive intelligent control strategy enables the entire system to automatically adjust operating parameters based on the varying operating conditions of the exhaust boiler 1, maintaining efficient and stable operation and maximizing energy efficiency.

[0085] When the load of the flue gas boiler 1 changes or is disturbed, in addition to the rapid and stable adjustment of the operating parameters through proportional-integral-differential adaptive adjustment, the flue gas flow rate is also a very important control parameter. By adjusting the speed of the flue gas fan, the flue gas flow rate can be adjusted, and then the waste heat recovery amount can be adjusted.

[0086] Regarding system installation and commissioning, the liquid slag cooling crusher 2 should be installed near the slag outlet of the slag boiler 1 to ensure smooth flow of liquid slag. Its foundation must be secure, and the cooling water piping connections must be tight and leak-proof. The dry-type heat exchanger 3 should be mounted on a suitable support and level. After installation, a pressure test should be performed to ensure no leaks.

[0087] When installing the air preheater 5, ensure that the air inlet duct of the cold air conveyor (i.e., the air intake blower) has sufficient air flow and is unobstructed, and the muffler is correctly positioned. The air filter is installed on the cold air conveyor's air inlet duct, and the filter elements of each level must be installed according to the required filtration accuracy. After installation, perform an air flow test to check the filtration effect. The shell-and-tube heat exchanger 4 is installed on a stable foundation. The connecting pipes between the shell and tube sides of the shell-and-tube heat exchanger 4 must be properly sealed, and the baffles of the shell-and-tube heat exchanger 4 must be securely installed.

[0088] When installing the control system, the temperature sensor should be installed in the designated location, ensuring that the sensor probe is in full contact with the measured medium, securely fixed, and correctly wired. The pressure sensor should be installed at a readily measurable pressure point on the pipeline and undergo a zero calibration after installation. The flow sensor should be installed in the designated location, ensuring measurement accuracy. The data acquisition device should be installed in the control cabinet. After connecting the sensor data cables, a data acquisition test should be performed to ensure proper data transmission. The control system should be installed in the control cabinet, and the preset proportional-integral-differential control algorithm and parameters should be input. After connecting to the actuator, a linkage test should be performed to verify the controller's control function over the actuator. After the system is installed, comprehensive commissioning should be performed to check the operating status of each device, pipeline connections, sensor data acquisition accuracy, and controller control functions to ensure proper system operation.

[0089] During the later stages of slag-destroying boiler 1's operation, as its load gradually decreases, the control system adjusts the air flow control valve opening accordingly based on data from various flow and temperature sensors, reducing unnecessary energy consumption and achieving energy-saving operation. Throughout operation, the control system continuously and adaptively adjusts the operating parameters of each device based on the real-time operating conditions of slag-destroying boiler 1, ensuring that the dry heat exchanger's efficient waste heat recovery and the air preheater are always operating in the optimal, adaptive, and stable state, improving the energy efficiency of slag-destroying boiler 1 and reducing environmental pollution.

[0090] After slag-draining boiler 1 has been operating for a while, its load gradually increases. For example, the temperature sensor in the combustion area of slag-draining boiler 1 detects a temperature drop, indicating incomplete combustion and the need for more heat input. Based on the data fed back by the temperature sensor and using an adaptive proportional-integral-differential control algorithm, the control system's controller determines that the exhaust fan speed of slag-draining boiler 1 needs to be increased. The controller then issues a command to the frequency converter of the exhaust fan to increase the speed, thereby increasing the exhaust flow rate of the boiler.

[0091] When the load of the slag-degassing boiler 1 gradually decreases in the later stage of its operation, the control system again determines the need to reduce heat input based on the data fed back by each temperature sensor and flow sensor, such as the temperature increase in the combustion area of the slag-degassing boiler 1. The controller reduces the exhaust fan speed of the slag-degassing boiler 1 by, for example, 40%, to reduce the exhaust flow of the slag-degassing boiler 1. At the same time, it adjusts the opening of each throttle valve accordingly to reduce the air flow. In this way, the air preheating temperature is reduced to 150°C, reducing unnecessary energy consumption and achieving energy-saving operation. Throughout the operation process, the control system adaptively and continuously adjusts the operating parameters of each device according to the real-time operating conditions of the slag-degassing boiler 1, ensuring that the dry heat exchanger and air preheater are always in the best adaptive and stable operating state, improving the energy utilization efficiency of the slag-degassing boiler 1 and reducing pollution to the environment.

[0092] 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. An adaptive liquid slag discharge boiler system based on waste heat utilization, comprising an air preheater (5), characterized in that: The first inlet of the air preheater (5) is connected to the cold air conveyor through a first conveying pipe, and the first conveying pipe is also connected to a second conveying pipe through a three-way electromagnetic valve a. The second conveying pipe is used to convey part of the cold air to the shell and tube heat exchanger (4) for heat exchange. After the heat exchange and temperature increase, the cold air passes through the three-way electromagnetic valve c and then a part enters the first-stage mixing device (6) through the fifth conveying pipe, and the other part passes through the three-way electromagnetic valve c and is discharged to the outside through the sixth conveying pipe; the first outlet of the air preheater (5) is connected to the first-stage mixer (6), and the slag discharge boiler (1) is connected to the exhaust pipe through the flue gas fan. The exhaust pipe The air preheater (5) is connected to the second inlet thereof and is used for exchanging heat with the cold air entering the air preheater (5) through the first delivery pipe. The second outlet of the air preheater (5) is connected to the third delivery pipe and the fourth delivery pipe respectively through the three-way solenoid valve b. The third delivery pipe is used to deliver part of the flue gas to the dry heat exchanger (3) for heat exchange with the liquid slag discharge. The flue gas after heat exchange in the dry heat exchanger (3) enters the shell and tube heat exchanger (4) for heat exchange. The flue gas delivered by the fourth delivery pipe is mixed with the flue gas after heat exchange in the shell and tube heat exchanger (4) in the secondary mixer (7) and then discharged after dust removal. A plurality of temperature sensors are respectively arranged at the inlet and outlet of the slag discharge boiler (1), the inlet and outlet of the dry heat exchanger (3), the inlet and outlet of the shell and tube heat exchanger (4), and the inlet and outlet of the air preheater (5); A plurality of flow sensors are respectively arranged on the first delivery pipe, the second delivery pipe, the third delivery pipe, the fourth delivery pipe, the fifth delivery pipe, the sixth delivery pipe and the smoke exhaust pipe; The control system is connected to the exhaust fan, each temperature sensor, each flow sensor, the three-way solenoid valve a, the three-way solenoid valve b and the three-way solenoid valve c respectively, and is used to control the speed of the exhaust fan and the opening of the three-way solenoid valve a, the three-way solenoid valve b and the three-way solenoid valve c according to the heat load in the slag discharge boiler (1).

2. The adaptive liquid slag removal boiler system based on waste heat utilization according to claim 1 is characterized in that: The shell side of the dry heat exchanger (3) is connected to the slag discharge boiler (1) via a liquid slag discharge cooling crusher (2). The outlet of the liquid slag discharge cooling crusher (2) is also provided with a temperature sensor, which is also connected to the control system.

3. The adaptive liquid slag removal boiler system based on waste heat utilization according to claim 1 is characterized in that: The outlet of the cold air conveyor is connected to an air filter.

4. The adaptive liquid slag discharge boiler system based on waste heat utilization according to claim 1 is characterized in that: The heat exchange tubes of the shell and tube heat exchanger (4) are stainless steel tubes, and a plurality of baffles are provided in the shell side of the shell and tube heat exchanger (4).

5. The adaptive liquid slag discharge boiler system based on waste heat utilization according to claim 1 is characterized in that: The shell and tube heat exchanger (4) and the fourth delivery pipe are both connected to a secondary mixing device (7), and the secondary mixing device (7) is connected to a discharge unit via a pipeline.

6. The adaptive liquid slag discharge boiler system based on waste heat utilization according to claim 5, characterized in that: The discharge unit comprises a dust collector (8), an induced draft fan (9), a desulfurization device (11) and a chimney (12); the dust collector (8) is connected to the induced draft fan (9) via a pipeline; the induced draft fan (9) is connected to a three-stage mixing device (10) via a pipeline; the three-stage mixing device (10) is connected to the desulfurization device (11) via a pipeline; the desulfurization device (11) is connected to the chimney (12) via a pipeline; and the sixth conveying pipe is also connected to the three-stage mixing device (10).

7. The adaptive liquid slag removal boiler system based on waste heat utilization according to claim 2, characterized in that: The liquid slag discharge cooling crusher (2) comprises a crushing chamber and a crushing tool, the crushing chamber is provided with a cooling jacket, and the crushing tool is made of a high-temperature resistant alloy material.

8. The method of the adaptive liquid slag discharge boiler system based on waste heat utilization according to claim 1, characterized in that: The steps include: A portion of the cold air conveyed by the cold air conveyor is conveyed into the air preheater (5) through the first conveying pipe, and is heat-exchanged with the flue gas conveyed into the air preheater (5) by the slag discharge boiler (1). The cold air after the heat exchange is converted into hot air a. A portion of the flue gas after the heat exchange is conveyed into the dry heat exchanger (3) through the third conveying pipe, and is heat-exchanged with the high-temperature liquid slag conveyed into the dry heat exchanger (3) by the slag discharge boiler (1). The flue gas after air quenching and heat exchange is sent into the shell side of the shell and tube heat exchanger (4) and exchanges heat with another part of the cold air sent into the tube side of the shell and tube heat exchanger (4) through the second delivery pipe by the cold air conveyor. The cold air after heat exchange becomes hot air b; a part of the hot air b is mixed with the hot air a at the first mixing device (6) through the fifth delivery pipe, and after mixing, it is sent to the slag discharge boiler (1) through the hot air delivery pipe for reuse. The other part of the hot air b is mixed with the flue gas discharged from the shell side of the shell and tube heat exchanger (4) after the heat exchange through the sixth delivery pipe and then discharged; The control system receives flow measurement value signals from the first conveying pipe, the second conveying pipe, the third conveying pipe, the fourth conveying pipe, the fifth conveying pipe, the sixth conveying pipe and the smoke exhaust pipe, as well as temperature measurement value signals from the inlet and outlet of the slag discharge boiler (1), the dry heat exchanger (3), the inlet and outlet of the shell and tube heat exchanger (4) and the inlet and outlet of the air preheater (5), and calculates the deviation between each temperature setting value and each temperature measurement value and the deviation between each flow setting value and each flow measurement value. According to the load demand of the combustion of the slag discharge boiler (1), the opening of the three-way solenoid valve a, the three-way solenoid valve b and the three-way solenoid valve c and the speed of the smoke exhaust fan are regulated to adjust the temperature of the air fed into the slag discharge boiler (1) when the load of the slag discharge boiler (1) changes.

9. The method of the adaptive liquid slag discharge boiler system based on waste heat utilization according to claim 8, characterized in that: The high-temperature liquid slag sent from the slagging boiler (1) into the dry heat exchanger (3) is crushed and cooled by the liquid slagging crusher (2).

10. The method of the adaptive liquid slag discharge boiler system based on waste heat utilization according to claim 8, characterized in that: The difference between each temperature and each flow rate is calculated using a proportional-differential-integral method, which includes the following steps: The temperature difference and the flow difference are calculated based on the measured values of temperature and flow obtained at the same time and the set values of temperature and flow; The currently obtained temperature difference or flow difference is compared with the positive and negative values using the proportional operation method to obtain a temperature control signal or a flow size control signal; The currently obtained temperature difference or flow difference is differentiated using a differential operation method to obtain a temperature change rate signal or a flow change rate signal; The currently obtained temperature difference or flow difference is integrated using an integration operation method to obtain a temperature cumulative deviation signal or a flow cumulative deviation signal; The signals obtained according to the above-mentioned proportional operation method, differential operation method and integral operation method are used to control the speed of the smoke exhaust fan and the opening of the three-way solenoid valve a, three-way solenoid valve b and three-way solenoid valve c.

Images