Plasma ash melting system and automatic control method thereof
阅读说明：本技术 一种等离子灰渣熔融系统及其自动控制方法 (Plasma ash melting system and automatic control method thereof ) 是由 宫臣 胡明 宗肖 李小明 齐景伟 虎训 赵彬 肖诚斌 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种等离子灰渣熔融系统及其自动控制方法,该系统包括：等离子炉；信号检测单元,用于检测熔渣深度、熔池温度和电弧电流信号；入料控制单元,用于调节对应入料口的入料量；逻辑运算单元,用于计算最佳电弧弧长、最佳输出功率和最佳电弧电压,进而计算最佳整流输出电压和最佳整流输出电流；电极位置控制单元,用于调节电极位置；整流控制单元,用于控制整流电源输出最佳整流输出电压和最佳整流输出电流；信号检测单元分别与等离子炉、入料控制单元和逻辑运算单元电连接；逻辑运算单元分别与电极位置控制单元和整流控制单元电连接。本发明有效解决了传统熔渣电极和供电控制系统输入功率不匹配、控制精度低、熔池均匀性差等问题。(The invention discloses a plasma ash melting system and an automatic control method thereof, wherein the system comprises: a plasma furnace; the signal detection unit is used for detecting slag depth, molten pool temperature and arc current signals; the feeding control unit is used for adjusting the feeding amount of the corresponding feeding port; the logic operation unit is used for calculating the optimal arc length, the optimal output power and the optimal arc voltage so as to calculate the optimal rectified output voltage and the optimal rectified output current; an electrode position control unit for adjusting the position of the electrode; the rectification control unit is used for controlling the rectification power supply to output the optimal rectification output voltage and the optimal rectification output current; the signal detection unit is respectively and electrically connected with the plasma furnace, the feeding control unit and the logic operation unit; the logic operation unit is electrically connected with the electrode position control unit and the rectification control unit respectively. The invention effectively solves the problems of mismatching of input power, low control precision, poor molten pool uniformity and the like of the traditional slag electrode and power supply control system.)
1. A plasma ash melting system, comprising:
the plasma furnace is used for generating electric arcs and melting ash;
the signal detection unit is used for detecting slag depth, molten pool temperature and arc current signals in the plasma furnace and transmitting detection signals;
the feeding control unit is used for adjusting the feeding amount of the plasma furnace corresponding to the feeding port according to the temperature of the molten pool at different positions in the plasma furnace;
the logic operation unit is used for calculating the optimal arc length, the optimal output power and the optimal arc voltage according to the detection signals, and further calculating the optimal rectified output voltage and the optimal rectified output current;
the electrode position control unit is used for adjusting the electrode position according to the optimal arc length;
the rectification control unit is used for controlling the output voltage and the output current of the rectification power supply to be the optimal rectification output voltage and the optimal rectification output current;
the signal detection unit is respectively and electrically connected with the plasma furnace, the feeding control unit and the logic operation unit; and the logic operation unit is electrically connected with the electrode position control unit and the rectification control unit respectively.
2. The automatic control method of the plasma ash melting system according to claim 1, characterized by comprising the following steps:
s1, a signal detection unit detects a slag depth signal in a plasma furnace and transmits the slag depth signal to a logic operation unit;
s2, calculating the optimal arc length of the electric arc by the logic operation unit according to the slag depth signal, and transmitting the optimal arc length to the electrode position control unit;
s3, adjusting the electrode position according to the optimal arc length by the electrode position control unit;
s4, detecting an arc current signal in the plasma furnace by a signal detection unit and transmitting the arc current signal to a logic operation unit;
s5, calculating an optimal arc voltage by the logic operation unit according to the optimal arc length and the optimal arc current, further calculating an optimal rectification output voltage, and transmitting the optimal rectification output voltage to the rectification control unit;
s6, detecting molten pool temperature signals at different positions in the plasma furnace by a signal detection unit, and transmitting the molten pool temperature signals to a logic operation unit and a feeding control unit;
s7, calculating the optimal output power by the logic operation unit according to the temperature of the molten pool and the optimal melting temperature of ash slag, further calculating the optimal rectification output current, and transmitting the optimal rectification output current to the rectification control unit; the feeding control unit adjusts the feeding amount of the corresponding feeding port on the plasma furnace according to the temperature of the molten pool at different positions in the plasma furnace;
s8, controlling the output voltage and the output current of the rectification power supply to be the optimal rectification output voltage and the optimal rectification output current by the rectification control unit;
s9, circulating steps S1-S8, and controlling the optimal arc length, the optimal rectified output voltage and the optimal rectified output current in real time.
3. The method of claim 2, wherein the method of detecting the slag depth signal in step S1 is an electrical signal measurement method or a fixed interval probing method.
4. The automatic control method of plasma ash melting system according to claim 2 characterized in that the optimum arc length L in step S2aThe calculation method comprises the following steps:
La＝k1Lr+b1
wherein k is1＝0.5～0.8；LrAs depth of molten pool, b1Is a constant.
5. The automatic control method of plasma ash melting system according to claim 2, characterized in that the optimum arc voltage V in step S5aThe calculation method comprises the following steps:
Va＝k2La-b2It-b3
wherein k is2＝0.6～1.2V/mm，LaFor optimum arc length, b2＝8～25V/Ka，ItIs arc current, b3Is a constant.
6. The automatic control method of plasma ash melting system according to claim 2, characterized in that the optimal rectified output voltage V in step S5dThe calculation method comprises the following steps:
wherein, VaFor optimum arc voltage, H is the system reactance, R is the system resistance, t is time, ItIs arc current, k3Is a constant.
7. The automatic control method of plasma ash melting system according to claim 2, characterized in that the optimal output power P in step S7aThe calculation method comprises the following steps:
Pa＝kΔt-b4
wherein k and b4Are all constants, and delta t is the absolute value of the difference between the bath temperature and the optimal melting temperature of the ash.
8. The automatic control method of plasma ash melting system according to claim 2, characterized in that the optimal rectified output current I in step S7aThe calculation method comprises the following steps:
wherein, PaFor optimum output power, VaIs the optimum arc voltage.
9. The automatic control method of a plasma ash melting system according to claim 2, characterized in that the bath temperature used for calculation in the step S7 is: the temperature value of the molten pool at any position in the plasma furnace or the weighted average value of the temperature of the molten pool at different positions in the plasma furnace.
10. The automatic control method of plasma ash melting system according to claim 2, characterized in that the method of controlling the feeding amount by the feeding control unit in step S7 is: and controlling the total feeding amount to be unchanged, and increasing the feeding amount of a feeding port corresponding to the position with lower temperature of the molten pool in the plasma furnace.
Technical Field
The invention belongs to the technical field of hazardous waste treatment, and particularly relates to a plasma ash melting system and an automatic control method thereof.
Background
Fly ash generated by burning household garbage and fly ash and bottom slag generated by burning hazardous waste belong to the category of hazardous waste, and the fly ash and the bottom slag are collectively called ash and slag. At present, the treatment mode aiming at the dangerous waste is mainly safe landfill and the cost is higher. The fly ash and the bottom slag can be innoxiously reduced, volume reduced and recycled by the plasma melting technology. In the process of heating, melting and vitrifying the dangerous waste fly ash and the bottom slag in the plasma melting furnace, electric energy is input into a molten pool in a heating mode of electric arc. In order to improve the heat distribution and the heat transfer rate of the molten pool, the running length of the electric arc and the depth of the molten pool are closely related, the electric arc is too long and can cause open arc, and the heat transfer efficiency is reduced and local overheating is caused if the electric arc is too short.
The existing arc control means generally adopts the following logic: the voltage and the current are used as a collecting signal source, the current and the voltage signal are used as set values, the voltage and the current signal of the system operation are collected and compared with the set values of the voltage and the current, and the electrode position and the rectification output power supply are properly adjusted to eliminate the direct difference between the measured value and the set value. However, since the voltage and current signals are not matched with the melting conditions such as basic temperature of the melting bath in the furnace, depth of the melting bath, heat distribution of the melting bath and the like, on one hand, the stability of the working conditions in the furnace is poor, and a supercooled or overheated area caused by mismatching of feeding and heating processes is easy to appear, and on the other hand, the matching of the electric arc and the melting bath is poor, so that the heating efficiency of the melting bath in the furnace is low, or the refractory material is damaged by open arc operation.
CN201710150920B discloses a submerged arc furnace electrode control method based on calculating furnace electrode effective load resistance. According to the technical scheme, equivalent circuit modeling of the power system of the silicomanganese ore heating furnace is achieved, all middle-path parameters such as effective load resistance in the furnace are calculated according to the equivalent circuit model, the control relation among the effective load resistance in the furnace, electrode control and power supply gateway active power is found, and the technical problem that the effective load resistance guides electrode control is solved. The electrode moving is controlled according to the effective load resistance of the calculated electrode, the calculation result is accurate, the error is small, the mutual influence of three-phase electrode operation of the power utilization system is small, the three-phase active power balance convergence speed is high, namely, when one phase electrode moves, the influence on the effective load resistance of the other two phases electrode is small. However, the invention adjusts parameters such as electrode position and the like by only depending on electrical signals in the system, does not combine the arc length with the spatial position relation of materials to be melted, and does not combine the input power with key states such as the temperature of a molten pool, so that the optimal matching arc length and the optimal power output state cannot be obtained.
Therefore, a new plasma ash melting system and an automatic control method thereof are required.
Disclosure of Invention
The technical problem to be solved is as follows: aiming at the technical problems, the invention provides a plasma ash melting system and an automatic control process thereof, which solve the problems of mismatching of input power, low control precision, poor molten pool uniformity and the like of the traditional slag electrode and power supply control system.
The technical scheme is as follows: a plasma ash melting system comprising:
the plasma furnace is used for generating electric arcs and melting ash;
the signal detection unit is used for detecting slag depth, molten pool temperature and arc current signals in the plasma furnace and transmitting detection signals;
the feeding control unit is used for adjusting the feeding amount of the plasma furnace corresponding to the feeding port according to the temperature of the molten pool at different positions in the plasma furnace;
the logic operation unit is used for calculating the optimal arc length, the optimal output power and the optimal arc voltage according to the detection signals, and further calculating the optimal rectified output voltage and the optimal rectified output current;
the electrode position control unit is used for adjusting the electrode position according to the optimal arc length;
the rectification control unit is used for controlling the output voltage and the output current of the rectification power supply to be the optimal rectification output voltage and the optimal rectification output current;
the signal detection unit is respectively and electrically connected with the plasma furnace, the feeding control unit and the logic operation unit; and the logic operation unit is electrically connected with the electrode position control unit and the rectification control unit respectively.
An automatic control method of a plasma ash melting system comprises the following steps:
s1, a signal detection unit detects a slag depth signal in a plasma furnace and transmits the slag depth signal to a logic operation unit;
s2, calculating the optimal arc length of the electric arc by the logic operation unit according to the slag depth signal, and transmitting the optimal arc length to the electrode position control unit;
s3, adjusting the electrode position according to the optimal arc length by the electrode position control unit;
s4, detecting an arc current signal in the plasma furnace by a signal detection unit and transmitting the arc current signal to a logic operation unit;
s5, calculating an optimal arc voltage by the logic operation unit according to the optimal arc length and the optimal arc current, further calculating an optimal rectification output voltage, and transmitting the optimal rectification output voltage to the rectification control unit;
s6, detecting molten pool temperature signals at different positions in the plasma furnace by a signal detection unit, and transmitting the molten pool temperature signals to a logic operation unit and a feeding control unit;
s7, calculating the optimal output power by the logic operation unit according to the temperature of the molten pool and the optimal melting temperature of ash slag, further calculating the optimal rectification output current, and transmitting the optimal rectification output current to the rectification control unit; the feeding control unit adjusts the feeding amount of the corresponding feeding port on the plasma furnace according to the temperature of the molten pool at different positions in the plasma furnace;
s8, controlling the output voltage and the output current of the rectification power supply to be the optimal rectification output voltage and the optimal rectification output current by the rectification control unit;
s9, circulating steps S1-S8, and controlling the optimal arc length, the optimal rectified output voltage and the optimal rectified output current in real time.
Preferably, the method for detecting the slag depth signal in step S1 is an electrical signal measurement method or a fixed-interval probing method.
Preferably, the optimal arc length L in step S2aThe calculation method comprises the following steps:
La＝k1Lr+b1
wherein k is1＝0.5～0.8；LrAs depth of molten pool, b1Is a constant.
Preferably, the optimal arc voltage V in step S5aThe calculation method comprises the following steps:
Va＝k2La-b2It-b3
wherein k is2＝0.6～1.2V/mm，LaFor optimum arc length, b2＝8～25V/Ka，ItIs arc current, b3Is a constant.
Preferably, the optimal rectified output voltage V in step S5dThe calculation method comprises the following steps:
wherein, VaFor optimum arc voltage, H is the system reactance, R is the system resistance, t is time, ItIs arc current, k3Is a constant.
Preferably, the optimal output power P in step S7aThe calculation method comprises the following steps:
Pa＝kΔt-b4
wherein k and b4Are all constants, and delta t is the absolute value of the difference between the bath temperature and the optimal melting temperature of the ash.
Preferably, the optimal rectified output current I in the step S7aThe calculation method comprises the following steps:
wherein, PaFor optimum output power, VaIs the optimum arc voltage.
Preferably, the molten pool temperature used for calculation in step S7 is: the temperature value of the molten pool at any position in the plasma furnace or the weighted average value of the temperature of the molten pool at different positions in the plasma furnace.
Preferably, the method for controlling the feeding amount by the feeding control unit in step S7 includes: and controlling the total feeding amount to be unchanged, and increasing the feeding amount of a feeding port corresponding to the position with lower temperature of the molten pool in the plasma furnace.
Has the advantages that: because of the particularity of plasma ash melting, the slag on the upper part of the metal layer is in a non-foaming state, the heat conduction capability is greatly superior to that of foam slag, the electric arc is wholly embedded into the slag, the heat conduction path is formed by conducting the electric arc to the slag and conducting the electric arc to the metal layer, the electric arc is too long and can cause open arc, the heat conduction efficiency is reduced if the electric arc is too short, and local overheating is caused.
By the method, the positive correlation between the arc length and the voltage value is fully considered, the output voltage of the rectification power supply is adjusted according to the required length of the arc, so that the output voltage of the rectification power supply can be always matched with the arc length required by operation, and the conditions of arc breakage, reduction or mismatching of power supply efficiency and the like are avoided.
The input power is determined according to the temperature difference value between the actual measurement temperature and the melting temperature of the molten pool, so that the melting process fluctuation caused by overhigh or overlow input power is avoided, meanwhile, the operation intensity of personnel is reduced, and the process control precision is improved.
Through analysis of thermal distribution of the molten pool, the appearance of overheating and supercooling areas is buffered by adjusting the matching of the feeding amount, the integral uniformity and controllability of the molten pool are improved, and the process stability of the melting process is improved.
Drawings
FIG. 1 is a schematic diagram of the control logic of the system of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings and specific embodiments.
Example 1
A plasma ash melting system comprising:
the plasma furnace is used for generating electric arcs and melting ash;
the signal detection unit is used for detecting slag depth, molten pool temperature and arc current signals in the plasma furnace and transmitting detection signals;
the feeding control unit is used for adjusting the feeding amount of the plasma furnace corresponding to the feeding port according to the temperature of the molten pool at different positions in the plasma furnace;
the logic operation unit is used for calculating the optimal arc length, the optimal output power and the optimal arc voltage according to the detection signals, and further calculating the optimal rectified output voltage and the optimal rectified output current;
the electrode position control unit is used for adjusting the electrode position according to the optimal arc length;
the rectification control unit is used for controlling the output voltage and the output current of the rectification power supply to be the optimal rectification output voltage and the optimal rectification output current;
the signal detection unit is respectively and electrically connected with the plasma furnace, the feeding control unit and the logic operation unit; and the logic operation unit is electrically connected with the electrode position control unit and the rectification control unit respectively.
As shown in fig. 1, the automatic control method based on the plasma ash melting system comprises the following steps:
s1, a signal detection unit detects a slag depth signal in a plasma furnace and transmits the slag depth signal to a logic operation unit;
s2, calculating the optimal arc length of the electric arc by the logic operation unit according to the slag depth signal, and transmitting the optimal arc length to the electrode position control unit;
s3, adjusting the electrode position by the electrode position control unit through hydraulic, electric or pneumatic means and the like according to the optimal arc length, so that space conditions can be created for the optimal state of melting operation;
s4, detecting an arc current signal in the plasma furnace by a signal detection unit and transmitting the arc current signal to a logic operation unit;
s5, calculating an optimal arc voltage by the logic operation unit according to the optimal arc length and the optimal arc current, further calculating an optimal rectification output voltage, and transmitting the optimal rectification output voltage to the rectification control unit;
s6, detecting molten pool temperature signals at different positions in the plasma furnace by a signal detection unit, and transmitting the molten pool temperature signals to a logic operation unit and a feeding control unit;
s7, calculating the optimal output power by the logic operation unit according to the temperature of the molten pool and the optimal melting temperature of ash slag, further calculating the optimal rectification output current, and transmitting the optimal rectification output current to the rectification control unit; the feeding control unit adjusts the feeding amount of the corresponding feeding port on the plasma furnace according to the temperature of the molten pool at different positions in the plasma furnace;
s8, controlling the output voltage and the output current of the rectification power supply to be the optimal rectification output voltage and the optimal rectification output current by the rectification control unit;
s9, circulating steps S1-S8, and controlling the optimal arc length, the optimal rectified output voltage and the optimal rectified output current in real time.
Specifically, the method for detecting the slag depth signal in step S1 is an electrical signal measurement method or a fixed-interval probing method.
Specifically, the optimum arc length L in step S2aThe calculation method comprises the following steps:
La＝k1Lr+b1
wherein k is1＝0.5～0.8；LrAs depth of molten pool, b1Is constant and is related to the material and the specific melting process.
Specifically, the optimum arc voltage V in step S5aThe calculation method comprises the following steps:
Va＝k2La-b2It-b3
wherein k is2＝0.6～1.2V/mm，LaFor optimum arc length, b2＝8～25V/Ka，ItIs arc current, b3Is constant and is related to the material and the specific melting process.
Specifically, the optimal rectified output voltage V in step S5dThe calculation method comprises the following steps:
wherein, VaFor optimum arc voltage, H is the system reactance, R is the system resistance, t is time, ItIs arc current, k3Is constant and is associated with a particular melting process.
Specifically, the optimal output power P in step S7aThe calculation method comprises the following steps:
Pa＝kΔt-b4
wherein k and b4Are all constants, k represents the power coefficient, b4Expressing the adjustment coefficient, at is the absolute difference between the bath temperature and the optimum melting temperature of the slagThe value is obtained.
Specifically, the optimal rectified output current I in step S7aThe calculation method comprises the following steps:
wherein, PaFor optimum output power, VaIs the optimum arc voltage.
Specifically, the molten pool temperature used for calculation in step S7 is: the temperature value of the molten pool at any position in the plasma furnace or the weighted average value of the temperature of the molten pool at different positions in the plasma furnace.
Specifically, the method for controlling the feeding amount by the feeding control unit in step S7 includes: and controlling the total feeding amount to be unchanged, and increasing the feeding amount of a feeding port corresponding to the position with lower temperature of the molten pool in the plasma furnace.
By the method of the invention, the length of the electric arc is combined with the depth of the molten pool, so that the uniformity and the stirring effect of the heating of the molten pool can be ensured.
By the method, the positive correlation between the arc length and the voltage value is fully considered, the output voltage of the rectification power supply is adjusted according to the required length of the arc, so that the output voltage of the rectification power supply can be always matched with the arc length required by operation, and the conditions of arc breakage, reduction or mismatching of power supply efficiency and the like are avoided.
The input power is determined according to the temperature difference value between the actual measurement temperature and the optimal melting temperature of the molten pool, so that the melting process fluctuation caused by overhigh or overlow input power is avoided, meanwhile, the operation intensity of personnel is reduced, and the process control precision is improved.
Through analysis of thermal distribution of the molten pool, the appearance of overheating and supercooling areas is buffered by adjusting the matching of the feeding amount, the integral uniformity and controllability of the molten pool are improved, and the process stability of the melting process is improved.
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