Non-afterburning type natural gas distributed energy waste heat utilization system and control method

Abstract

The invention relates to the technical field of waste heat utilization in the ceramic industry, and discloses a non-afterburning type natural gas distributed energy waste heat utilization system control method. When a natural gas generator set and hot blast stove mixed hot air supply spray tower and working condition switching are carried out, four valves act according to corresponding action strategies; opening of a main flue and closing of a bypass chimney, closing of the main flue and opening of the bypass chimney and opening of a branch pipeline under special conditions are controlled respectively; in the operation process, the main control unit adjusts the output load of the hot-blast stove based on the high-temperature flue gas flow collection assembly, the second temperature collection assembly and the tower top temperature collection assembly or independently based on the tower top temperature collection assembly, and further adjusts the output load of the hot-blast stove based on the data difference between the first temperature collection assembly and the second temperature collection assembly. The structure of the system is not only convenient to transform, but also beneficial to the accuracy of temperature control of the spray tower and the stability of switching among different working conditions of the whole system.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat utilization in the ceramic industry, and in particular to a non-supplementary combustion type natural gas distributed energy waste heat utilization system and a control method. Background Art

[0002] The dry powder process of the ceramic industry will have a large demand for fuel. The fuel for the dry powder process of the traditional ceramic industry is provided by external natural gas, diesel, coal or homemade water gas. The fuel is burned in the hot air furnace and heated to the set temperature before being sent to the spray tower to dry the slurry in the spray tower. Ceramic production requires a highly stable and continuous supply of heat energy to ensure the consistency of product quality and production efficiency. Although the hot air furnace can provide a stable heat source, this method has low energy utilization and high energy costs for enterprises.

[0003] To solve this problem, distributed energy technology can be used to achieve cascaded energy utilization on the user side, minimize the loss of dry powder process, and maximize energy utilization. For example, foreign countries use the "distributed energy + supplementary combustion" method to achieve green production in the ceramic industry, that is, using natural gas generators to generate electricity, and high-temperature flue gas mixed with sufficient air is supplemented through the flue supplementary burner to the required temperature and then sent to the spray tower. This method completely replaces the traditional hot air furnace and can achieve precise control of the tower top temperature.

[0004] However, this method is not suitable for domestic ceramic production enterprises. As a traditional heating equipment, the hot air furnace has a long history in the ceramic industry, and its technology is mature and reliable. In contrast, the hot air furnace system that completely abandons mature technology requires a large technical transformation and high cost. It may be difficult for some domestic small and medium-sized enterprises to bear, and the differences in existing technologies may make it difficult to implement. In addition, the domestic ceramic industry cannot adopt this technical route for transformation due to the requirements of "heat-based electricity" for distributed projects and stable production needs.

[0005] Therefore, how to combine distributed energy and hot air furnaces and adopt the "distributed energy + non-supplementary combustion" method to provide thermal energy has become a difficult problem that domestic ceramic manufacturers need to overcome. Summary of the invention

[0006] The present invention aims to provide a non-supplementary natural gas distributed energy waste heat utilization system and control method, which can achieve economically feasible technical transformation on the basis of retaining the traditional hot air stove, ensure the stable switching of multiple working conditions of the natural gas generator set, spray tower and hot air stove system, and provide stable and high-quality hot air for the spray tower.

[0007] The basic scheme provided by the present invention is: a non-supplementary combustion type natural gas distributed energy waste heat utilization system, including a main flue, a natural gas generator set, a hot air furnace, a spray tower and a main control unit;

[0008] The hot blast furnace is connected to the spray tower and has a connection port on the connection path; the smoke exhaust end of the natural gas generator set is connected to the connection port through the main flue; along the direction from the smoke exhaust end to the connection port, the main flue is provided with a bypass chimney and a branch pipeline connected to the atmosphere in sequence; the bypass chimney is provided with a first valve; on the main flue, and between the bypass chimney and the branch pipeline, a second valve and a third valve are provided, the second valve is located between the bypass chimney and the third valve, and the second valve and the third valve have a first distance; the branch pipeline is provided with a fourth valve;

[0009] The exhaust port of the natural gas generator set is provided with a first data acquisition component, including a first pressure acquisition component, a first temperature acquisition component and a high-temperature flue gas flow acquisition component; the connection port is provided with a second data acquisition component, including a second pressure acquisition component and a second temperature acquisition component; the spray tower is provided with a tower top temperature acquisition component;

[0010] The natural gas generator set, hot air furnace, spray tower, first data acquisition component, second data acquisition component, tower top temperature acquisition component, first valve, second valve, third valve and fourth valve are all communicatively connected to the main control unit and controlled by the main control unit; the first pressure acquisition component and the fourth valve are interlocked and controlled by the main control unit.

[0011] Based on the non-supplementary combustion type natural gas distributed energy waste heat utilization system, the present invention also provides a non-supplementary combustion type natural gas distributed energy waste heat utilization system control method, the method comprising:

[0012] When the natural gas generator set and the hot blast furnace mix hot air to supply the spray tower and the working condition is switched, the first valve, the second valve, the third valve and the fourth valve act according to the corresponding action strategy, respectively controlling the opening of the main flue and the closing of the bypass chimney, controlling the closing of the main flue and the opening of the bypass chimney, and controlling the opening of the branch pipeline under special circumstances;

[0013] During operation, the main control unit adjusts the output load of the hot blast furnace based on the high-temperature flue gas flow acquisition component, the second temperature acquisition component and the tower top temperature acquisition component, or based solely on the tower top temperature acquisition component, so that the total hot air temperature entering the spray tower is within the required range; the main control unit also makes a first abnormality judgment based on the temperature data difference measured by the first temperature acquisition component and the second temperature acquisition component; the main control unit also makes a second abnormality judgment based on the pressure data difference measured by the first pressure acquisition component and the second pressure acquisition component.

[0014] The working principle and advantages of the present invention are:

[0015] Ceramic enterprises produce in three shifts without stopping the furnace, which has extremely high requirements for system stability. At the same time, ceramic production has demanding requirements, and the drying temperature and moisture content of the finished product are relatively demanding. The fluctuation range of the tower top temperature is required to be within 5°C, and the fluctuation range of the finished product moisture content is within 0.5%. In particular, the precise temperature control requirements are very high, which directly affects the production quality of ceramics. The characteristics of the generator set itself cause the exhaust temperature of the generator set to fluctuate with the ambient temperature and its own load. Therefore, on the basis of the traditional hot air furnace supplying the spray tower, after adding distributed energy, how to maximize the use of waste heat, while ensuring both stable switching of the system and precise temperature control, is a technical difficulty.

[0016] Unlike the supplementary combustion form, this solution adopts a non-supplementary combustion form, does not add an additional supplementary burner, and does not abandon the hot blast furnace. Instead, it retains the original spray tower and hot blast furnace system and connects to the natural gas generator set. Through the reasonable design of the connection method and control logic, in addition to the original method of only using the hot blast furnace + external fuel to supply the spray tower, it adds the method of using the unit's flue gas supply and the unit and the hot blast furnace to jointly supply the spray tower, realizing an economically feasible energy-saving and carbon-reduction transformation method. At the same time, it is beneficial to the stability of switching between different operating conditions of the entire system, as well as the accuracy and rapidity of the spray tower temperature control, ensuring high-quality and energy-efficient production of ceramics, and providing a new transformation idea for the ceramic industry.

[0017] The advantages of this scheme's non-supplementary combustion method are:

[0018] 1) Make the most of the existing resources of ceramic enterprises. Compared with adding flues and afterburners and abandoning the afterburning method of the hot blast furnace, this solution only adds flues and connects the natural gas generator set to the original hot blast furnace and spray tower system, and almost no hardware technical changes are made to the original hot blast furnace and spray tower system. The transformation is easy, low cost and small investment; at the same time, the design of the flue is conducive to reducing the temperature fluctuation of the flue gas at the tail of the natural gas generator set, which is conducive to temperature regulation.

[0019] In conventional ceramic production, the spray tower and hot air furnace are located in the factory, while the natural gas generator sets are mostly located outside the factory, at a certain distance. If the heat is transported through multiple branch flues or multiple pipelines, it is easy to cause heat loss. In addition, due to the structural characteristics of the conventional hot air furnace itself, it is very difficult or even impossible to connect the branch flue to the hot air furnace for transformation. Therefore, whether it is to reduce the waste heat transmission loss, the feasibility of technical transformation, or to consider the accuracy of the spray tower temperature control in the later stage, and the stability of switching between different working conditions of the entire system, this scheme retains the original hot air furnace and spray tower structure, and connects the natural gas generator set to the connection port of the hot air furnace and the spray tower with an independent flue. The flue gas of the natural gas generator set and the hot air of the hot air furnace are mixed at the connection port and then sent into the spray tower. This is an effective and economically feasible energy-saving and carbon-reduction transformation method in the existing ceramic production equipment layout.

[0020] 2) The designed control strategy and temperature control strategy have the advantages of both stable system switching and precise temperature control.

[0021] This solution is based on the reasonable arrangement of bypass chimneys and branch pipes in the main flue, and the reasonable configuration and layout optimization of valves and data acquisition components. Through the designed control logic, different action sequences of valves are switched under different working conditions, which realizes the stable switching of multiple working conditions and ensures the stable production of the enterprise.

[0022] In particular, the second valve and the third valve installed between the bypass chimney and the branch pipeline are difficult to achieve zero leakage after a period of operation for large-caliber, high-temperature flue gas valves. After air leaks into the flue gas system, it is easy to interfere with the temperature control inside the spray tower when the spray tower is running independently. The second valve and the third valve form a double insurance to ensure that no air leaks into the main flue when the spray tower or the unit is running separately and independently, avoiding interference or impact on the spray tower system and ensuring the stable operation of the spray tower. In addition, the control strategy of the opening and closing sequence of the second and third valves when switching between different working conditions can ensure the stability of the working condition switching, avoid system instability caused by emergency stop and emergency switching, and damage to the generator set. Therefore, the second and third valves are the core components to achieve the overall stable linkage of the system and ensure the precise temperature control of the original system of the enterprise after the construction of this system.

[0023] The temperature control of traditional hot air furnaces is to increase or decrease the number of burner guns started in the hot air furnace according to the temperature of the spray tower to adjust the temperature. At the same time, the temperature is also adjusted manually by experience to achieve manual adjustment of the air inlet opening of the hot air furnace shell. After the air inlet opening of the shell is adjusted, it is generally not adjusted. Although this type of adjustment can basically meet the needs through experience, there is only a single one-to-one combination of temperature monitoring and adjustment points. Once a problem occurs at a certain node, the temperature accuracy cannot be guaranteed.

[0024] On the basis of ensuring the stable switching of system operating conditions, this solution adds digital acquisition components at the beginning and end of the main flue to form multiple monitoring points. It can not only realize data collection and data mutual verification at multiple points to ensure the safe operation of the system, but also through the designed temperature control strategy, it can adjust the temperature based on data from different points under different operating conditions and different stages of the same operating conditions, which is conducive to ensuring the accuracy and rapidity of temperature regulation. At the same time, the design of the flue is conducive to reducing the temperature fluctuation of the flue gas at the tail of the natural gas generator set, avoiding a large temperature regulation span, and ensuring high-quality production of ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a non-supplementary combustion type natural gas distributed energy waste heat utilization control system provided by an embodiment of the present invention;

[0026] Figure 2 The operation process of a non-supplementary combustion type natural gas distributed energy waste heat utilization control system provided by the embodiment of the present invention Figure 1 ;

[0027] Figure 3 The operation process of a non-supplementary combustion type natural gas distributed energy waste heat utilization control system provided by the embodiment of the present invention Figure 2 ;

[0028] Figure 4 The operation process of a non-supplementary combustion type natural gas distributed energy waste heat utilization control system provided by the embodiment of the present invention Figure 3 ;

[0029] Figure 5 The operation process of a non-supplementary combustion type natural gas distributed energy waste heat utilization control system provided by the embodiment of the present invention Figure 4 ;

[0030] Figure 6 The operation process of a non-supplementary combustion type natural gas distributed energy waste heat utilization control system provided by the embodiment of the present invention Figure 5 ;

[0031] Figure 7 The operation process of a non-supplementary combustion type natural gas distributed energy waste heat utilization control system provided by the embodiment of the present invention Figure 6 ;

[0032] Figure 8 The operation process of a non-supplementary combustion type natural gas distributed energy waste heat utilization control system provided by the embodiment of the present invention Figure 7 . DETAILED DESCRIPTION

[0033] The following is a further detailed description through specific implementation methods:

[0034] Embodiment 1

[0035] Basically as attached Figure 1 Shown: A non-supplementary combustion type natural gas distributed energy waste heat utilization control system, including a main flue, a natural gas generator set (referred to as the unit), a hot air furnace, a spray tower and a main control unit.

[0036] It should be noted that this scheme can be based on the transformation of the hot blast furnaces and spray towers and their corresponding systems that have been built or are to be built in existing ceramic enterprises. On the basis of minimizing the transformation of the original hot blast furnaces and spray towers, economically feasible energy-saving and carbon-reduction transformation can be carried out, which is suitable for application in most ceramic enterprises; the main control unit represents the entire control system, which is transformed accordingly on the basis of meeting the mature operating modes of conventional hot blast furnaces and spray towers, and the corresponding control strategy of this scheme is used to utilize the waste heat of the natural gas engine group into the original system of the hot blast furnace and spray tower of the ceramic enterprise, and ensure the stable operation of the hot blast furnace and spray tower; this scheme emphasizes and protects the connection structure, and does not limit the specific internal connection method of the main control unit. It can be reasonably set and transformed based on the effect that this device wants to achieve, which can be achieved using existing control technology.

[0037] The hot blast furnace is connected to the spray tower and has a connection port on the connection path; the smoke exhaust end of the natural gas generator set is connected to the connection port through the main flue, so that the smoke of the natural gas generator set can be input into the spray tower through the connection port; along the direction from the smoke exhaust end to the connection port, the main flue is sequentially provided with a bypass chimney and a branch pipeline connected to the atmosphere, and the bypass chimney should be as close to the natural gas generator set as possible to ensure normal startup of the generator set.

[0038] Specifically, the length of the main flue should be controlled within 200m, and the diameter is determined according to the diameter of the exhaust port of the generator set. In this embodiment, the main flue is about 160m long, with an outer diameter of 1760mm and an inner diameter of 1200mm. The insulation materials are insulation cotton + high-aluminum polylight ball bricks from outside to inside to ensure that the waste heat of the natural gas generator set can be input into the spray tower with the smallest possible loss, thereby improving the utilization rate of thermal energy. At the same time, the diameter is set reasonably to meet the maximum allowable back pressure of the generator set while ensuring that the negative pressure point in the main flue is as far away from the generator set as possible to ensure safe access. It can be said that directly accessing the connection port with an independent flue is currently a very effective and feasible technical transformation method based on the original system.

[0039] Gas turbines can be used for natural gas generator sets. They have a slightly lower power generation efficiency, but have a high exhaust temperature, a large exhaust volume, and a large amount of waste heat, making them more suitable for energy cascade utilization scenarios with heating as the main purpose. Units with flue gas temperatures above 500°C account for 68.5%, and units with flue gas temperatures above 450°C account for 93.8%. The exhaust gas is close to the demand of the spray tower (usually required to be between 550 and 650°C), and the waste heat is fully utilized. In addition, gas turbines do not require frequent maintenance, and the lubricating oil only needs to be replaced once a year, which can fully meet the production arrangement needs of the enterprise and is more in line with the production needs of the spray tower that requires long-term continuous and stable operation.

[0040] The bypass chimney is provided with a first valve D1 for controlling the opening and closing of the bypass chimney. In this embodiment, the bypass chimney is 1.75m away from the exhaust port of the generator set, and the first valve is 2.5m away from the branch tee between the main flue and the bypass chimney. This setting allows the generator set to be started in a shorter time.

[0041] A second valve D2 and a third valve D3 are provided on the main flue and between the bypass chimney and the branch pipeline. The opening and closing of the two valves control the opening and closing of the main flue. The second valve D2 and the third valve D3 have a first distance. The first distance should ensure that when the second valve D2 and the third valve D3 are fully opened, the distance between their valve plates is not less than 300mm to ensure the normal opening and closing of the two valves. The distance between the second valve D2 and the bypass chimney should be controlled at 2 to 3m to reduce the influence of the main flue system on the generator set when it is operating independently. An expansion joint should be set on the main flue between D2 and the bypass chimney to prevent the back-end system from exerting force on the bypass chimney due to thermal expansion and contraction.

[0042] A fourth valve Q1 is provided on the branch pipeline to control the opening and closing of the branch pipeline to prevent air from leaking into the main flue and interfering with the temperature control in the spray tower.

[0043] The first valve D1, the second valve D2 and the third valve D3 are fully open and fully closed electric high-temperature flue gas butterfly valves, the third valve D3 is a fully open and fully closed electric high-temperature flue gas butterfly valve or a step-adjustable electric high-temperature flue gas butterfly valve, and the fourth valve Q1 is a fully open and fully closed pneumatic high-temperature flue gas butterfly valve. The fully open and fully closed type means that it is 100% open after opening and 100% closed after closing.

[0044] The maximum threshold value of the operating temperature of the first valve, the second valve, the third valve and the fourth valve is not less than 700°C, and the leakage rate is less than 1.5%, so as to ensure that the valves can operate normally and stably at the exhaust temperature corresponding to different loads of the generator set (including the exhaust temperature when the unit is started).

[0045] The exhaust port of the natural gas generator set is provided with a first data acquisition component, including a first pressure acquisition component (i.e., a first pressure sensor P1), a first temperature acquisition component (i.e., a first temperature sensor T1) and a high-temperature flue gas flow acquisition component (i.e., a high-temperature flue gas flowmeter F1); the connection port is provided with a second data acquisition component, including a second pressure acquisition component (i.e., a second pressure sensor P2) and a second temperature acquisition component (i.e., a second temperature sensor T2); the spray tower is provided with a tower top temperature acquisition component (i.e., a tower top temperature sensor T3). Due to the large diameter of the flue, for accurate measurement, it is recommended that each sensor be arranged in 2 to 3 groups evenly on the flue diameter.

[0046] The natural gas generator set, hot air furnace, spray tower, first data acquisition component, second data acquisition component, tower top temperature acquisition component, first valve, second valve, third valve and fourth valve are all communicatively connected to the main control unit and controlled by the main control unit; the first pressure acquisition component and the fourth valve are interlocked and controlled by the main control unit.

[0047] During the specific operation process, the data of the first data acquisition component, the second data acquisition component and the tower top temperature acquisition component are transmitted to the main control device, that is, the flue gas pressure, flue gas temperature and flue gas flow at the unit exhaust port are monitored respectively through P1, T1 and F1; the flue gas pressure and flue gas temperature at the main flue connection port are monitored respectively through P2 and T2; and T3 is used to feedback whether the temperature in the spray tower reaches the required operating conditions.

[0048] The hot air furnace mainly uses T2, T3 and F1, or T3 alone to feedback and adjust the hot air furnace load, and then adjust the hot air temperature; P1 and P2 are mainly used for pressure monitoring, especially negative pressure monitoring, to ensure the safe connection between the natural gas generator set and the spray tower. The main logical relationship of the system is as follows:

[0049] T1: Mainly used for unit exhaust temperature monitoring and forming a mutual confirmation relationship with T2. When the difference between T1 and T2 exceeds the theoretical temperature drop range of the system (this temperature drop range is a theoretical value calculated based on the length, diameter, insulation material performance and thickness of the system main flue. Of course, in the system design process, the theoretical difference between T1 and T2 should be minimized as much as possible under economic feasibility), there are two situations: (1) Normal situation: During operation, due to the attenuation of material performance, the difference gradually decreases. This process is a process calculated in months or years and is a normal phenomenon. During this process of material performance attenuation, the computer preset parameters of the hot air furnace need to be corrected regularly, which is part of the normal maintenance of the system. (2) Abnormal situation: The difference suddenly increases beyond a certain range. At this time, the control system needs to alarm. This situation is mostly caused by flue leakage or the erroneous opening of any valve of D1 or Q1. Of course, T1 also has the function of providing data for the temperature adjustment of the hot air furnace, but it is not the main one. The hot air furnace is mainly adjusted by T2 and T3.

[0050] T2: Mainly used to interlock with the hot air stove computer to adjust the hot air stove combustion gun load to stabilize the temperature in the spray tower. At the same time, T2 also needs to be verified with T1 to eliminate system failures, as described in the previous paragraph.

[0051] T3: Temperature monitoring inside the spray tower is used to determine whether the hot blast furnace combustion gun is increasing or decreasing the load.

[0052] P1: A safety element to ensure that the generator set is not damaged by negative pressure, interlocked with Q1. At the same time, it can be mutually verified with P2 to exclude damage to the flue system or accidental opening of the valve, the same as T1.

[0053] P2: Feedback of measured value, confirmed with P1. In addition, feedback of sudden change of rear pressure, such as failure of the exhaust fan of the spray tower but no error report, can be identified and alarmed by the sudden decrease or disappearance of negative pressure at P2.

[0054] F1: Feedback to the hot air furnace computer together with T2 measurement value, interlocking to adjust the hot air furnace combustion gun load to stabilize the temperature in the spray tower. In addition, it can also assist the heat supply settlement between energy companies and ceramic enterprises, that is, calculate the heat supply through real-time T2 and F1. However, due to the low accuracy of F1, the heat supply calculated in this way is only used as a reference for settlement.

[0055] The main control unit adjusts the action of the control components according to the control strategy based on the F1, T1, P1, T2, P2 parameter data and other operating data of the current spray tower, hot blast stove, and natural gas generator set. The control components are controlled by the main control device to control the corresponding valves to change their states in an orderly manner. It is used to control the opening of the main flue and the closing of the bypass chimney, or the closing of the main flue and the opening of the bypass chimney. It is also used to control the opening of branch pipelines under special circumstances to match them with the required working conditions of the natural gas generator set, hot blast stove, and spray tower, realize working condition switching, temperature adjustment, so as to ensure the stable operation of the entire system under different working conditions. For example Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 shown.

[0056] Working condition 1: The flue gas discharged from the natural gas generator set and the hot air discharged from the hot blast furnace are mixed at the connection port and transported to the top of the spray tower to supply hot air to the inside of the spray tower. This working condition is also the main operating mode of this system.

[0057] like Figure 2 As shown, it starts with the natural gas generator set, hot air furnace, and spray tower not started. During the startup process, the startup status needs to be confirmed first. D1 is in the open state, D2, D3, and Q1 are in the closed state, and the hot air furnace and spray tower are ready. When the natural gas generator set is started, it needs to be isolated from the rear spray tower first, so the bypass chimney (ie D1) needs to be connected to the atmosphere. Q1 should be kept closed for a long time (branch pipeline closed) to prevent air from leaking into the system. When shutting down or stopping due to a fault, only P1 needs to be interlocked. P1 reaches the lower limit of the allowable pressure at the exhaust end of the generator set before Q1 is interlocked and opened quickly.

[0058] After the status is confirmed, a start signal is sent to the natural gas generator set, and the natural gas generator set starts to start. It can only be slowly connected to the system after the load is stabilized to 70%. The reason is that the unit has requirements for the back pressure at the rear end, and the back pressure that can be tolerated at the start is relatively small. After the load is increased to 70%, D2 is turned on, and after it is fully opened, D3 is turned on; the opening status of D3 is determined. If a fault is reported, the system is in the current state and the fault is eliminated (if it is a major fault (such as the generator cannot operate normally, or D3 cannot be opened normally at all, etc.), the system will be completely stopped according to the corresponding safety regulations). After the fault is eliminated, the current natural gas generator set is running stably, and the load continues to be increased to full load, and then D1 is closed. After it is fully closed, it is ensured that the natural gas generator set is running stably.

[0059] The spray tower is started in two stages. The first stage start-up may include starting the exhaust fan, spraying water in the tower, and drying the tower. After the flue gas from the natural gas generator set is connected (that is, after D2 and D3 are turned on), the first stage start-up of the spray tower begins to dry the tower. It is judged that the spray tower drying is completed and the natural gas generator set is running stably. At this time, the second stage start-up of the spray tower is continued, that is, the hot air furnace is started until the spray tower is running stably as a whole. The operation of the spray tower requires the temperature to be controlled within the range of ±5℃.

[0060] Specifically, the hot blast furnace is started, and the load is gradually increased according to the preset load increase strategy until the operation is stable, that is, the load is increased according to the hot blast furnace output load calculated according to the exhaust gas temperature when the unit is fully loaded. During the load increase process, the hot blast furnace determines and adjusts the output load target value according to F1, T2, and T3 through the main control device, so that T3 reaches the required temperature range of the spray tower; when the hot blast furnace is running stably, the spray tower is running stably, and the unit is fully loaded, it is confirmed that the current operation of the entire system is stable, and thus enters the working condition 1 in which the natural gas generator set and the hot blast furnace simultaneously supply hot air to the spray tower, and then the hot blast furnace fine-tunes the temperature according to T3. During the load increase process, the hot blast furnace determines and adjusts the load to T3 to reach the required range with F1, T2 and T3, and then fine-tunes the temperature with T3 after the common supply system is running stably. In this way, the temperature regulation of the common supply system is more direct and rapid.

[0061] In order to improve the accuracy and speed of temperature adjustment, T1, T2 and F1 can also be continuously monitored while adjusting the hot blast furnace according to T3. When T1 exceeds the preset alarm threshold, for example, the fluctuation range exceeds ±10°C, it means that the flue gas temperature fluctuates greatly. Immediately restore and adjust the output load target value according to F1, T2 and T3, so as to predict temperature changes in advance and avoid the adjustment lag problem caused by load adjustment according to T3 in the case of large fluctuations. After T1 and T3 return to the stable range, resume fine-tuning according to T3.

[0062] The stable operation of the spray tower is very important. The whole system emphasizes stability because the powder dried in the spray tower is an important production raw material. The value of a furnace of powder is millions of yuan. Once the working condition is unstable, the powder parameters will not meet the standard, resulting in losses. Unit load adjustment will cause changes in exhaust temperature (load reduction, reduced exhaust volume but increased exhaust temperature). At this time, T2, T3, and F1 need to be fed back to the hot air furnace computer to adjust the output load of the hot air furnace. Therefore, under the condition of stable operation, if Figure 3 As shown in the figure, it is the working condition switching from working condition 1 to unit load adjustment. When the unit sends a load adjustment signal, the spray tower receives the signal and determines whether it meets the supply switching conditions. If not, the unit load adjustment is rejected, and the unit continues to maintain the original full load supply; if satisfied, it is confirmed, and the spray tower performs material conservation operation while the unit performs load adjustment. T3 feeds back the current temperature of the spray tower to the hot blast furnace, and the hot blast furnace feeds back to the hot blast furnace computer based on T2, T3, and F1 to adjust the output load of the hot blast furnace until the unit, spray tower and hot blast furnace operate stably and the working condition switching is completed.

[0063] In the case of stable operation, if Figure 2 As shown in the figure, it is the working condition switching from working condition 1 to normal shutdown of the unit. When the unit sends a unit shutdown signal, the spray tower receives the signal and determines whether it meets the supply switching conditions. If not, the unit shutdown is rejected, and the unit continues to supply at full load; if satisfied, the hot blast furnace starts to add load to independently supply the spray tower (the load is added at this time, and the adjustment is based on the feedback from T3 to the hot blast furnace computer), and D1 is turned on at the same time. After it is fully opened, the natural gas generator set shuts down normally. When the shutdown operation begins, D3 is closed (at this time, D1 is already opened, and the unit exhaust has been connected to the atmosphere. D3 should be used to cut off and isolate the unit from the spray tower-hot blast furnace system as soon as possible). After it is fully closed, D2 is closed. After it is fully closed, the working condition switching ends. At this time, the unit shuts down, and the hot blast furnace independently supplies the spray tower.

[0064] In the case of stable operation, if Figure 4As shown in the figure, the working condition switching from working condition 1 to unit failure emergency stop, the unit sends a fault signal, the spray tower sound and light alarm, T3 feeds back the current temperature of the spray tower to the hot blast furnace, the hot blast furnace adjusts the temperature of the combustion gun based on T3 calculation, and implements material conservation treatment; the spray tower sound and light alarm is turned on at the same time, and after it is fully opened, D3 is closed, and after it is fully closed, D2 is closed; while D1 is turned on, if P1 detects that the pressure is lower than the minimum allowable back pressure of the unit, Q1 is interlocked to open; until the spray tower and hot blast furnace run stably, the working condition switching is completed. In addition, when the unit fails, other sound and light alarms are also made through the main control unit, such as the sound and light alarm in the control room. The process of this working condition switching is different from the normal shutdown condition of the unit. In the control process, the rejection and confirmation links of the spray tower are reduced, and the hot blast furnace is directly used to supply the spray tower alone, which emphasizes the rapid and stable working condition switching and the rapid and accurate temperature adjustment.

[0065] In the case of stable operation, if Figure 5 As shown, it is the working condition switching from working condition 1 to spray tower failure. When the spray tower fails, the hot air furnace starts the corresponding stop operation after receiving the fault signal and quickly enters the shutdown state; at the same time, D1 is turned on, and after it is fully opened, the current state of the unit is confirmed, and D3 is closed. During the process of closing D3, the current state of the unit is confirmed. After D3 is fully closed, D2 is closed to confirm the current state of the unit. The current state confirmation of the unit requires judging whether the unit is directly shut down or continues to run independently after being disconnected from the rear-end spray tower system; when D1 is turned on, if P1 is lower than the allowable value of the unit, Q1 is turned on; until the unit runs independently and stably or shuts down normally, D2 is fully closed, and the working condition switching is completed. The failure of the spray tower itself requires more stable and fast switching than the failure of the unit.

[0066] like Figure 6 As shown, the operating condition is switched from the complete shutdown of the system to the flue maintenance. The shutdown status of the unit is confirmed, and the unit start button is locked. At the same time, the shutdown status of the spray tower and the hot blast furnace is confirmed, and the start buttons of the spray tower and the hot blast furnace are locked. After all locks are confirmed, D1, D2 and D3 are turned on to carry out flue maintenance. After the maintenance is completed, all locks are released and the operating condition switching is completed.

[0067] like Figure 7 and Figure 8 As shown, before the natural gas generator set is operated alone, and the spray tower-hot air furnace is operated alone, confirm that D1 is turned on, and D2 and D3 are turned off. After this condition is met, the corresponding startup process is carried out. The respective startup processes have been described in detail above and will not be repeated here.

[0068] The non-supplementary combustion type natural gas distributed energy waste heat utilization system provided in this embodiment adopts a non-supplementary combustion form, does not add additional supplementary burners and their supporting pipelines and components, does not need to change the installation layout, retains the existing equipment layout, and only requires a main flue to connect the unit flue gas discharge end and the spray tower-hot blast furnace connection port. It is estimated that the transformation cost can be saved by no less than 30%, realizing economic transformation. The transformation technology and cost are suitable for large, medium and small ceramic enterprises, and have a wide range of applications.

[0069] Because the spray tower has a negative pressure source, it is key to ensure the safe connection between the unit and the spray tower hot air furnace after connecting to the unit. Through the reasonable design of the length and diameter of the main flue, it is ensured that the waste heat of the natural gas generator set can be input into the spray tower with the smallest possible loss, thereby improving the utilization rate of thermal energy. At the same time, while meeting the maximum allowable back pressure of the generator set, the negative pressure point in the main flue is kept as far away from the generator set as possible to ensure safe connection.

[0070] After the natural gas unit is added, the operating conditions become more complicated. By designing the control strategy, the start and stop of the natural gas generator set, the opening and closing of the flue, the operation of the spray tower and the adjustment of the hot blast furnace are closely linked and carried out in an orderly manner. At the same time, the distance setting and interlocking relationship of the bypass chimney, branch pipeline and valve can enable the generator set to be started in a shorter time to ensure the safe docking of the natural gas generator set and the spray tower and stable exit.

[0071] Data monitoring and temperature regulation: when the natural gas generator set is a gas turbine, 68.5% of the units have flue gas temperatures above 500°C, and 93.8% of the units have flue gas temperatures above 450°C. The exhaust gas is close to the spray tower demand (usually required at 550-650°C), and is mixed with the hot blast furnace outlet air, so that the hot blast furnace can quickly meet the spray tower temperature demand with a smaller load in a shorter time, and quickly and accurately make the tower top temperature fluctuate within the required range of ±5°C. The special design of the data acquisition components at the flue gas discharge end, the connection port and the spray tower monitors the data of important parameters during operation. During the unit connection process, the hot air parameters of the hot blast furnace are adjusted based on F1, T2 and T3. After the unit is connected and running stably and during the independent supply of the hot blast furnace, the hot air parameters of the hot blast furnace are adjusted based on T3 alone, so that the hot blast furnace can adjust the combustion gun in real time to maintain the temperature in the spray tower stable, and meet the requirements quickly and accurately; the flue gas discharge of the natural gas engine unit is relatively stable. Although the flue gas temperature fluctuates within the range of about ±10℃, due to the reasonable design of the flue length and diameter of this scheme, a slight fluctuation will not be so drastic because of the efficient heat dissipation of the material. Therefore, after the system runs stably, the hot blast furnace can quickly meet the temperature requirements by fine-tuning according to T3. This is also a special effect of the flue design on temperature control. In addition, based on the data difference measured by T1 and T2, P1 and P2, abnormal judgment is made, and the working condition adjustment is done in time to ensure stable operation.

[0072] This solution not only saves costs but also improves the system's operating efficiency and thermal energy utilization rate through non-supplementary combustion transformation. Through the carefully designed main flue, operating condition management and temperature adjustment strategy, the stable operation of the system and the precise control of the temperature in the spray tower are ensured.

[0073] Embodiment 2

[0074] On the basis of the first embodiment, the hot blast furnace is provided with at least one load-adjustable combustion gun; the temperature in the conventional hot blast furnace is adjusted by increasing or decreasing the number of combustion guns. When the combustion gun is in use, the temperature of the spray cannot be adjusted in real time with the operation of the system, so the adjustment accuracy needs to be improved.

[0075] This scheme sets at least one load-adjustable burner, which is mainly adjusted by adjusting the load of a single burner and supplemented by increasing or decreasing the number of burners. That is, the temperature rise of the burner during the operating condition adjustment process is mainly load adjustment, that is, the temperature is mainly adjusted by one burner, unless the load of the unit drops sharply and the load adjustment of one burner cannot meet the requirement, then consider adding one or more burners, so that the temperature adjustment of the whole system adds an adjustable point, further improving the accuracy of temperature adjustment. In addition, real-time adjustment through a load-adjustable burner makes temperature control simpler and more convenient than adding multiple burners, and the adjustment process is faster and more stable.

[0076] Embodiment 3

[0077] On the basis of embodiments one and two, a non-supplementary combustion type natural gas distributed energy waste heat utilization control system also includes a fuel supply device connected to the supply input end of the natural gas generator set. The fuel supply device meters, stabilizes (or regulates) the pressure of the natural gas supplied from the municipal pipeline, and boosts the pressure to the pressure required by the natural gas generator set before delivering it to the natural gas generator set for use.

[0078] The system also includes a compressed air supply device connected to the valves belonging to the natural gas generator set and the fourth valve to provide a valve control power source therefor.

[0079] The system also includes a flue gas monitoring device installed on the bypass chimney. The compressed air supply device is also connected to the flue gas monitoring device on the bypass chimney to provide a purge air source for the sampling facility.

[0080] Of course, the natural gas generator set is also connected to the electrical system, security, fire protection and other systems, and the layout and setting are made according to actual needs to ensure the normal and stable operation of the natural gas generator set when it operates independently without heating to generate electricity.

[0081] Embodiment 4

[0082] Different from the first, second and third embodiments, the third valve D3 is an electric high-temperature flue gas butterfly valve with graded adjustable opening. After the system is built, the appropriate opening is determined in the debugging stage and used as the preset opening (which can be 100% or other openings). Under normal circumstances, the preset opening is no longer adjusted. In actual operation, the third valve D3 is opened to the preset opening, closed to full close, and slowly opened and closed at a preset rate, that is, after opening or closing, it moves at a rate of about 5 to 10 minutes to reach 100% opening or 100% closing, and can be stopped at the current opening at any time through control, which can ensure that the fluctuations in the process can be effectively dealt with when the system operating conditions are switched, and the fault can be removed in time when a fault occurs.

[0083] Compared with the second valve and the third valve which are both fully open and fully closed valves, after the third valve is replaced with a valve with graded opening adjustment, from the perspective of the entire system, an adjustable point is added. When the flue diameter or material setting is not reasonable and the flue resistance is insufficient, the valve can be set to be adjustable to increase the resistance to ensure that the generator set will not have negative pressure, so as to adjust the main flue resistance to adapt to the stability of the overall system operation.

[0084] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field are aware of all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement the scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for the ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. Non-supplementary natural gas distributed energy waste heat utilization system, It is characterized in that It includes main flue, natural gas generator set, hot air stove, spray tower and main control unit; The hot blast furnace is connected to the spray tower and has a connection port on the connection path; the smoke exhaust end of the natural gas generator set is connected to the connection port through the main flue; along the direction from the smoke exhaust end to the connection port, the main flue is provided with a bypass chimney and a branch pipeline connected to the atmosphere in sequence; the bypass chimney is provided with a first valve; on the main flue, and between the bypass chimney and the branch pipeline, a second valve and a third valve are provided, the second valve is located between the bypass chimney and the third valve, and the second valve and the third valve have a first distance; the branch pipeline is provided with a fourth valve; The exhaust port of the natural gas generator set is provided with a first data acquisition component, including a first pressure acquisition component, a first temperature acquisition component and a high-temperature flue gas flow acquisition component; the connection port is provided with a second data acquisition component, including a second pressure acquisition component and a second temperature acquisition component; the spray tower is provided with a tower top temperature acquisition component; The natural gas generator set, hot air furnace, spray tower, first data acquisition component, second data acquisition component, tower top temperature acquisition component, first valve, second valve, third valve and fourth valve are all communicatively connected to the main control unit and controlled by the main control unit; the first pressure acquisition component and the fourth valve are interlocked and controlled by the main control unit.

2. According to the non-supplementary combustion type natural gas distributed energy waste heat utilization system of claim 1, It is characterized in that The hot blast stove is provided with at least one load-adjustable combustion gun.

3. Control method of non-supplementary natural gas distributed energy waste heat utilization system, It is characterized in that The waste heat utilization system of non-supplementary combustion type natural gas distributed energy waste heat utilization according to any one of claims 1-2 is used for waste heat utilization, and the method comprises: When the natural gas generator set and the hot blast furnace mix hot air to supply the spray tower and the working condition is switched, the first valve, the second valve, the third valve and the fourth valve act according to the corresponding action strategy, respectively controlling the opening of the main flue and the closing of the bypass chimney, controlling the closing of the main flue and the opening of the bypass chimney, and controlling the opening of the branch pipeline under special circumstances; During operation, the main control unit adjusts the output load of the hot blast furnace based on the high-temperature flue gas flow acquisition component, the second temperature acquisition component and the tower top temperature acquisition component, or based solely on the tower top temperature acquisition component, so that the total hot air temperature entering the spray tower is within the required range; the main control unit also makes a first abnormality judgment based on the temperature data difference measured by the first temperature acquisition component and the second temperature acquisition component; the main control unit also makes a second abnormality judgment based on the pressure data difference measured by the first pressure acquisition component and the second pressure acquisition component.

4. According to the control method of the non-supplementary combustion type natural gas distributed energy waste heat utilization system of claim 3, It is characterized in that When the natural gas generator set and the hot blast furnace mix hot air to supply the spray tower, first confirm that the first valve is in the open state, and the second valve, the third valve and the fourth valve are in the closed state; after the state is confirmed, start the natural gas generator set, add the load to the preset load, first open the second valve, then open the third valve, and the main flue is opened; after the third valve is fully opened, the natural gas generator set continues to add the load to full load, then close the first valve, and the bypass chimney is closed; The main flue is opened, and the flue gas enters the spray tower and starts to dry the tower; after the tower drying is completed, the first valve is closed in place, and the natural gas generator set is running stably, the hot air furnace is started and the load is gradually increased according to the load increase strategy; the main control unit adjusts the output load of the hot air furnace based on the high-temperature flue gas flow collection component, the second temperature collection component and the tower top temperature collection component.

5. According to the control method of the non-supplementary combustion type natural gas distributed energy waste heat utilization system of claim 3, It is characterized in that When the natural gas generator set and the hot air furnace are mixed to supply the spray tower with hot air, the unit sends a shutdown signal. If the spray tower confirms it, the first valve is opened, the bypass chimney is opened, and the hot air furnace is loaded to supply the spray tower independently. The main control unit adjusts the output load of the hot air furnace based on the tower top temperature acquisition component. After the first valve is opened in place, the natural gas generator set starts the normal shutdown operation. During the shutdown operation, the third valve is closed first, and then the second valve, and the main flue is closed.

6. The control method of the non-supplementary combustion type natural gas distributed energy waste heat utilization system according to claim 3, It is characterized in that When the natural gas generator set and the hot air furnace mix to supply the spray tower with hot air, the natural gas generator set sends a load adjustment signal. If the spray tower confirms it, the spray tower will perform material conservation operation. At the same time, the natural gas generator set performs load adjustment. The main control unit adjusts the output load of the hot air furnace based on the tower top temperature acquisition component.

7. The control method of the non-supplementary combustion type natural gas distributed energy waste heat utilization system according to claim 3, It is characterized in that When the natural gas generator set and the hot blast furnace mix hot air to supply the spray tower, the unit sends a unit fault signal, the spray tower alarms, and the main control unit adjusts the hot blast furnace output load based on the tower top temperature acquisition component, and the first valve is opened, the third valve is closed, and the second valve is closed in sequence; when the first valve is opened, if the data measured by the first pressure acquisition component is lower than the allowable value of the unit, the fourth valve is opened and the branch pipeline is opened.

8. The control method of the non-supplementary combustion type natural gas distributed energy waste heat utilization system according to claim 3, It is characterized in that When the natural gas generator set and the hot blast furnace mix hot air to supply the spray tower, the spray tower fails and the hot blast furnace stops working. At the same time, the first valve is opened, the third valve is closed, and the second valve is closed in sequence. After the first valve is closed and during the closing of the third valve, the current state of the natural gas generator set is confirmed to determine whether the current natural gas generator set enters independent operation or normal shutdown; when the first valve is opened, if the data measured by the first pressure acquisition component is lower than the unit operation value, the fourth valve is opened and the branch pipeline is opened.

9. The control method of the non-supplementary combustion type natural gas distributed energy waste heat utilization system according to claim 3, It is characterized in that The method further includes, when the main flue needs to be repaired, first confirming that the natural gas generator set, the spray tower and the hot blast furnace are in a shutdown state and the start button is locked, opening the first valve, the second valve and the third valve, and repairing the main flue, and after the repair is completed, the lock of the start button of the natural gas generator set, the spray tower and the hot blast furnace is released; Before the natural gas generator set is operated alone, and before the spray tower-hot air furnace is operated alone, confirm that the first valve is open, and the second and third valves are closed. After this condition is met, the corresponding startup process is carried out.

10. The control method of the non-supplementary combustion type natural gas distributed energy waste heat utilization system according to claim 3, It is characterized in that The methods for adjusting the output load of the hot blast furnace include a method of adjusting only the number of combustion guns, and a method of mainly adjusting the load of a single combustion gun and supplemented by increasing or decreasing the number of combustion guns.

Images