TOCS boiler denitration control system and control method

Abstract

The invention relates to a TOCS boiler denitration control system which comprises a programming station, an MOC controller, a DCS system, a DCS operator station and a boiler combustion system, the programming station and the MOC controller carry out data exchange through an MODBUS communication protocol, the MOC controller and the DCS system carry out data exchange through the MODBUS communication protocol, the DCS system and the DCS operator station carry out data exchange through the MODBUS communication protocol, and the DCS operator station carries out data exchange through the boiler combustion system. And the DCS system and the boiler combustion system exchange data through a MODBUS communication protocol. The denitration intelligent optimization control system can realize compatible communication with different types of DCS systems, can effectively improve control of denitration NOX indexes, achieves the purposes of energy conservation and consumption reduction while ensuring that the NOX concentration does not exceed the standard, and can be widely popularized to coal-fired units of the same type.

Description

Technical Field

[0001] The present invention relates to the technical field of boiler denitration, and in particular to a TOCS boiler denitration control system and a control method. Background Art

[0002] Coal-fired boilers in thermal power plants are used to meet the NO X To meet emission requirements, flue gas denitrification treatment is carried out. For the sake of technical maturity and economic considerations, selective non-catalytic reduction (SNCR) or selective catalytic reduction (SCR) is generally used. Both processes inject a certain concentration of ammonia (NH 3 ), change NO X Reduction to N 2 and H 2 O.

[0003] During the denitrification process, it is necessary to ensure that the treated flue gas NOX meets the emission standards, that is, lower than a certain value, while preventing excessive ammonia from escaping into the atmosphere and causing ammonia pollution to the atmosphere. This requires automatic operation to adapt to various changes in boiler operating conditions.

[0004] The current denitrification automatic control strategies are all based on the denitrification efficiency. According to the original flue gas NOX situation, the operator sets a suitable denitrification efficiency. The system calculates the amount of ammonia that should be injected into the denitrification device under the current flue gas flow rate based on this efficiency to achieve automatic control of denitrification. This strategy uses PID to achieve closed-loop control. During use, the variables are relatively single and can only adapt to the changing working conditions of the flue gas volume. And because it is a closed-loop control, there are always fluctuations in a certain amplitude and period during steady-state control and slow response to dynamic changes in working conditions. This is limited by the PID algorithm of single-variable control and is an irreconcilable contradiction. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a TOCS boiler denitration control system and a control method.

[0006] In the first aspect of the present invention, a TOCS boiler denitrification control system is provided, including a programming station, a MOC controller, a DCS system, a DCS operator station and a boiler combustion system. The programming station and the MOC controller exchange data through the MODBUS communication protocol, the MOC controller and the DCS system exchange data through the MODBUS communication protocol, the DCS system and the DCS operator station exchange data through the MODBUS communication protocol, and the DCS system and the boiler combustion system exchange data through the MODBUS communication protocol. The MOC controller obtains the unit operation data from the DCS system, gives the optimal control instructions after calculation, and controls the corresponding actuators through the DCS system. This system adopts a modular graphic configuration method, which can complete complex artificial intelligence algorithms and control configurations such as conventional control, fuzzy control, neural network control and expert control, and can be used for system operation analysis, simulation calculation and optimization control of various complex systems.

[0007] In a second aspect of the present invention, a TOCS boiler denitration control method is provided, comprising the following steps:

[0008] (1) Use the boiler fuel model to calculate the NO X The estimated value of the change is used to obtain a soft measurement result to overcome the NO X The measuring instrument has a slow response when sampling and measuring; at the same time, NO X The measurement results are used to perform long-term correction fitting on the soft measurement, so that the soft measurement results are verified and corrected by the hard measurement results, and a more accurate and timely soft measurement result is recursively obtained;

[0009] (2) According to the emission requirements of the environmental protection management department, the appropriate denitrification efficiency setting value is calculated, and after the range is limited, the larger value is output with the efficiency setting value set by the operator to obtain the most reasonable final optimization setting value of the denitrification efficiency of the system. In this way, the efficiency value set by the operator is actually a safe lower limit value, and the denitrification efficiency setting value will no longer be changed at any time according to the boiler operating conditions during operation;

[0010] (3) The system is based on NO X The estimated value and efficiency optimization setting value are used to instantly calculate the system optimized ammonia injection flow value, and the optimized ammonia flow is injected into the flue gas for denitrification reaction to obtain a relatively stable denitrification output NO X index;

[0011] (4) The system is based on the denitrification outlet NO X Indicators and ammonia escape conditions can be used to timely correct the denitrification efficiency setting value; since this system is mainly open-loop control, supplemented by long-term parameter closed-loop correction, it can achieve fast adjustment speed without oscillation.

[0012] The beneficial effects of the present invention are:

[0013] 1. The MOC controller communicates with the DCS system using MODBUS. The MOC controller obtains the unit operation data from the DCS system and finds out the NO X The estimated value of the change is used to obtain a soft measurement result to overcome the NO X The measuring instrument has a slow response to sampling. X The estimated value and efficiency optimization setting value can instantly calculate the system optimized ammonia injection flow value to control the ammonia injection valve, and obtain a relatively stable denitrification output NO X This system is mainly based on open-loop control, supplemented by long-term parameter closed-loop correction, which can achieve fast adjustment speed without oscillation.

[0014] 2. The denitrification intelligent optimization control system can achieve compatible communication with different types of DCS systems and can effectively improve denitrification NO X The control of indicators ensures NO X The concentration does not exceed the standard while achieving the goal of energy saving and consumption reduction, and can be widely promoted to the same type of coal-fired units.

[0015] 3. Denitration outlet NO of TOCS boiler denitration intelligent optimization control system X The change is less than 30 mg / m 3 .

[0016] 4. It can adapt to the working conditions of rapid changes in boiler load, such as when AGC is put into use, the outlet NO X It will not exceed the standard.

[0017] 5. Reduce the amount of ammonia escape, thereby reducing the blockage of the air preheater caused by ammonia crystallization in the furnace and the pollution to the atmosphere.

[0018] 6. Reduce the consumption of denitrification ammonia and improve the economic efficiency of denitrification.

[0019] 7. It can be applied to coal-fired boilers in power plants using the selective non-catalytic reduction method (SNCR) or the selective catalytic reduction method (SCR), which can improve the qualified rate of emissions during operation and improve the economic efficiency of operation at the same time.

[0020] 8. The optimization of denitrification control of Unit 3 of Laicheng Power Plant has improved the stability and reliability of the denitrification automatic control system, and the flue gas NO X The emission standards were met, environmental pressure was relieved, monitoring pressure on operators was reduced, liquid ammonia consumption was reduced, and denitrification economy was improved. In view of the good performance of the optimized system, the denitrification control of Unit 1 of Laicheng Power Plant was optimized, and the effect was equally obvious. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is a control principle block diagram of the present invention;

[0022] Figure 2 The NO at the outlet of the clean flue gas before the denitration control system of the present invention is put into operation X Change comparison curve chart;

[0023] Figure 3 The net NO at the flue gas outlet after the denitration control system of the present invention is put into operation X Change comparison curve chart; DETAILED DESCRIPTION

[0024] In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0025] like Figure 1-3 As shown, the TOCS boiler denitrification control system includes a programming station, a MOC controller, a DCS system, a DCS operator station and a boiler combustion system. The programming station and the MOC controller exchange data through the MODBUS communication protocol, the MOC controller and the DCS system exchange data through the MODBUS communication protocol, the DCS system and the DCS operator station exchange data through the MODBUS communication protocol, and the DCS system and the boiler combustion system exchange data through the MODBUS communication protocol. The MOC controller obtains the unit operation data from the DCS system, gives the optimal control instructions after calculation, and controls the corresponding actuators through the DCS system. This system adopts a modular graphic configuration method, which can complete complex artificial intelligence algorithms and control configurations such as conventional control, fuzzy control, neural network control and expert control, and can be used for system operation analysis, simulation calculation and optimization control of various complex systems.

[0026] In a second aspect of the present invention, a TOCS boiler denitration control method is provided, comprising the following steps:

[0027] (1) Use the boiler fuel model to calculate the NO X The estimated value of the change is used to obtain a soft measurement result to overcome the NO X The measuring instrument has a slow response when sampling and measuring; at the same time, NO X The measurement results are used to perform long-term correction fitting on the soft measurement, so that the soft measurement results are verified and corrected by the hard measurement results, and a more accurate and timely soft measurement result is recursively obtained;

[0028] (2) According to the emission requirements of the environmental protection management department, the appropriate denitrification efficiency setting value is calculated, and after the range is limited, the larger value is output with the efficiency setting value set by the operator to obtain the most reasonable final optimization setting value of the denitrification efficiency of the system. In this way, the efficiency value set by the operator is actually a safe lower limit value, and the denitrification efficiency setting value will no longer be changed at any time according to the boiler operating conditions during operation;

[0029] (3) The system is based on NO X The estimated value and efficiency optimization setting value are used to instantly calculate the system optimized ammonia injection flow value, and the optimized ammonia flow is injected into the flue gas for denitrification reaction to obtain a relatively stable denitrification output NO X index;

[0030] (4) The system is based on the denitrification outlet NO X Indicators and ammonia escape conditions can be used to timely correct the denitrification efficiency setting value; since this system is mainly open-loop control, supplemented by long-term parameter closed-loop correction, it can achieve fast adjustment speed without oscillation.

[0031] The MOC controller communicates with the DCS system using MODBUS. The MOC controller obtains the unit operation data from the DCS system and finds out the NO X The estimated value of the change is used to obtain a soft measurement result to overcome the NO X The measuring instrument has a slow response to sampling. X The estimated value and efficiency optimization setting value can instantly calculate the system optimized ammonia injection flow value to control the ammonia injection valve, and obtain a relatively stable denitrification output NO X This system is mainly based on open-loop control, supplemented by long-term parameter closed-loop correction, which can achieve fast adjustment speed without oscillation.

[0032] The denitrification intelligent optimization control system can achieve compatible communication with different types of DCS systems and can effectively improve the denitrification NO X The control of indicators ensures NO X The concentration does not exceed the standard while achieving the goal of energy saving and consumption reduction, and can be widely promoted to the same type of coal-fired units.

[0033] Of course, the above description is not limited to the above examples. Technical features not described in the present invention can be achieved by or by using existing technologies, which will not be described here. The above embodiments and drawings are only used to illustrate the technical scheme of the present invention and are not limitations of the present invention. The present invention is described in detail with reference to the preferred implementation methods. Ordinary technicians in this field should understand that changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention do not depart from the purpose of the present invention, and should also fall within the scope of protection of the claims of the present invention.

Claims

1.TOCS boiler denitrification control system, characterized by: It includes a programming station, MOC controller, DCS system, DCS operator station and boiler combustion system. The programming station and MOC controller exchange data through the MODBUS communication protocol, the MOC controller and DCS system exchange data through the MODBUS communication protocol, the DCS system and DCS operator station exchange data through the MODBUS communication protocol, and the DCS system and boiler combustion system exchange data through the MODBUS communication protocol. 2.TOCS boiler denitrification control method, characterized in that: The steps include: (1) Use the boiler fuel model to calculate the NO X The estimated value of the change is used to obtain a soft measurement result to overcome the NO X The measuring instrument has a slow response when sampling and measuring; at the same time, NO X The measurement results are used to perform long-term correction fitting on the soft measurement, so that the soft measurement results are verified and corrected by the hard measurement results, and a more accurate and timely soft measurement result is recursively obtained; (2) According to the emission requirements of the environmental protection management department, the appropriate denitrification efficiency setting value is calculated, and after the range is limited, the larger value is output with the efficiency setting value set by the operator to obtain the most reasonable final optimization setting value of the denitrification efficiency of the system. In this way, the efficiency value set by the operator is actually a safe lower limit value, and the denitrification efficiency setting value will no longer be changed at any time according to the boiler operating conditions during operation; (3) The system is based on NO X The estimated value and efficiency optimization setting value are used to instantly calculate the system optimized ammonia injection flow value, and the optimized ammonia flow is injected into the flue gas for denitrification reaction to obtain a relatively stable denitrification output NO X index; (4) The system is based on the denitrification outlet NO X Indicators and ammonia escape conditions can be used to timely correct the denitrification efficiency setting value; since this system is mainly open-loop control, supplemented by long-term parameter closed-loop correction, it can achieve fast adjustment speed without oscillation.

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