CN104896166A - Electric control adjusting system of conical valve of circulating fluidized bed boiler external type heat exchanger - Google Patents

Abstract

The invention discloses an electric control adjustment system for a conical valve of an external heat exchanger of a circulating fluidized bed boiler, which solves the problem that the conical valve is prone to jamming and blocking. The set value module, switching module, adder module, subtractor module, memory generator module, delay module, pulse module and dead zone module in the distributed control system are adopted. In order to prevent the cone valve from being blocked by dust particles, the valve position of the cone valve cannot always be kept at the same position. On the basis of the output, the appropriate offset and pulse control are superimposed as the final valve oscillation output. At the same time, when the deviation between the cone valve opening command and the position feedback is within the dead zone, the control system does not perform pulse oscillation output and maintains The existing opening avoids frequent oscillation of the cone valve. Especially suitable for field use.

Description

Electric Control Regulating System of Cone Valve for External Heat Exchanger of Circulating Fluidized Bed Boiler

technical field

The present invention relates to an electronically controlled regulating system for valves, in particular to an electrically controlled regulating system for cone valves in external heat exchangers of circulating fluidized bed boilers.

Background technique

As an important representative of clean coal technology, circulating fluidized bed combustion can realize direct desulfurization in the furnace combustion process and effectively suppress the emission of nitrogen oxides. It has strong adaptability to coal types and has been widely used. Circulating fluidized bed boilers are divided into two types: those with external heat exchangers and those without external heat exchangers. For the circulating fluidized bed with external heat exchanger, part of the materials separated by the cyclone separator will be directly returned to the furnace through the feeder, and the other part will pass through the external heat exchangers (external bed) arranged on both sides of the furnace. ), and then return to the furnace for secondary combustion. The superheater and reheater heating surface are arranged in the external bed of this type of circulating fluidized bed boiler. Bed temperature, to maintain the bed temperature of the circulating fluidized bed in the best state of low emission and high combustion efficiency. A return cone valve is set between the separator and the external bed. The return cone valve is the only passage through which the material separated by the cyclone separator enters the external bed. The opening of the return cone valve is controlled by adjustment. , can achieve the adjustment of the ratio of the external bed and the recirculation ash in the combustion chamber, and realize the adjustment of the boiler bed temperature and the steam temperature at the reheat outlet. When the unit is running stably, the valve opening of the cone valve remains basically unchanged, but if the valve of the cone valve stays at a certain opening for a long time, due to the long-term accumulation of circulating ash materials, the valve will be stuck. If the valve opening of the cone valve is adjusted frequently, the furnace temperature of the circulating fluidized bed boiler will be unstable, so that the bed temperature cannot be maintained at the best state of low emission and high combustion.

Contents of the invention

The invention provides an electric control adjustment system for the conical valve of the external heat exchanger of the circulating fluidized bed boiler, which solves the problem that the conical valve is prone to jamming and blocking, that is, it ensures that the valve will not be in a certain opening Staying for a long time, and avoiding the technical problem of unstable operation of the unit caused by the frequent vibration of the cone valve.

The present invention solves the above technical problems through the following technical solutions:

An electric control adjustment system for a conical valve of an external heat exchanger of a circulating fluidized bed boiler, including a conical valve opening position sensor, a set value module, a switching module, an adder module, a subtractor module, and a memory generator module , delay module, pulse module, dead zone module; the output end of the valve opening position sensor of the cone valve is connected with the first input end of the subtractor module, and the input command signal of the electric control baffle of the cone valve is connected with the subtractor module The second input terminal of the module is connected together, the output terminal of the subtractor module is connected together with the input terminal of the dead zone module, the output terminal of the dead zone module is connected together with the first input setting terminal S of the memory generator module, and the memory The output terminal of the generator module is connected with the input terminal of the delay module, the output terminal of the delay module is connected with the input terminal of the pulse module, the output terminal of the pulse module is connected with the second input reset terminal R of the memory generator module Connected together, the output terminal of the set value module is connected with the first input terminal of the adder module, the input command signal of the electric control baffle of the cone valve is connected with the second input terminal of the adder module, and the adder module The output terminal of the memory generator module is connected with the first input terminal of the switching module, the input command signal of the electric control baffle of the cone valve is connected with the second input terminal of the switching module, the output terminal of the memory generator module is connected with the switching terminal of the switching module connected together, the output end of the switching module is connected with the electronic control unit for the valve opening of the cone valve.

The dead zone module is a dead zone module with a fixed value of 2%. When the dead zone is greater than 2%, the output of the dead zone module is 1; when the dead zone is less than 2%, the output of the dead zone module is 0; the set value module is a setpoint module with a setpoint of 3%.

The invention avoids the jamming and blocking phenomenon of the conical valve of the large-scale circulating fluidized bed boiler equipped with an external bed, and at the same time avoids the problem of unstable unit operation caused by the frequent vibration of the conical valve. In order to prevent the cone valve from being blocked by dust particles, the valve position cannot always be kept at the same position. The control principle is that the setting value of the position set point is oscillating and changing. The cone valve opening command is based on the original control strategy control output. Above, the appropriate offset and pulse control are superimposed as the final valve oscillation output. At the same time, in order to avoid the frequent oscillation of the cone valve, when the deviation between the cone valve opening command and the position feedback is within the dead zone, the control system will not Perform pulse oscillation output to maintain the existing opening.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Figure 2 is a summary table of the characteristics of the modules used in the present invention.

Detailed ways

The present invention is described in detail below in conjunction with accompanying drawing:

An electric control adjustment system for a conical valve of an external heat exchanger of a circulating fluidized bed boiler, including a conical valve opening position sensor M9, a set value module M6, a switching module M8, an adder module M7, and a subtractor module M1 , memory generator module M3, time delay module M4, pulse module M5, dead zone module M2; the output terminal of the valve opening position sensor M9 of the cone valve is connected with the _first input terminal i1 of the subtractor module M1, and the cone The input command signal P of the electronically controlled baffle of the shaped valve is connected with the _second input terminal i2 of the subtractor module M1, and the output terminal O1 _of the subtractor module M1 is connected with the input terminal _i3 of the dead zone module M2. The output terminal _O2 of the district module M2 is connected together with the first input setting terminal S of the memory generator module M3, and the output terminal _O3 of the memory generator module M3 is connected together with the input terminal _i4 of the delay module M4, _The output terminal _O4 of the delay module M4 is connected together with the input terminal i5 of the pulse module M5, the output terminal _O5 of the pulse module M5 is connected together with the second input reset terminal R of the memory generator module M3, and the set value The output terminal O6 of the module _M6 is connected together with the first input terminal _i6 of the adder module M7, the input command signal P of the electric control baffle of the cone valve is connected together with the second input terminal _i7 of the adder module M7, _The output terminal O7 of the adder module M7 is connected together with the first input terminal _i8 of the switching module M8, the input instruction signal P of the electric control baffle of the cone valve is connected together with the second input terminal _i9 of the switching module M8, _The output terminal _O3 of the memory generator module M3 is connected with the switching terminal S1 _of the switching module M8, and the output terminal O8 of the switching module M8 is connected together with the valve opening electric control unit of the cone valve.

The dead zone module M2 is a dead zone module with a fixed value of 2%. When the dead zone is greater than 2%, the output of the dead zone module is 1; when the dead zone is less than 2%, the output of the dead zone module is 0; the set value Module M6 is a setpoint module with a setpoint of 3%.

The output signal of the cone valve valve opening position sensor M9 and the input command signal P of the cone valve electric control baffle are introduced into the subtractor module M1 for difference calculation, and introduced into the dead zone module M2, when the difference is less than the dead zone setting value 2 %, it can be considered that the valve action of the cone valve is sensitive and no jamming occurs, and no pulse oscillation output is performed at this time.

When the difference between the output signal of the valve opening position sensor M9 of the cone valve and the input command signal P of the cone valve electric control baffle is greater than 2% of the dead zone setting value, it can be judged that the cone valve is stuck. The memory generator module M3 is set to perform pulse oscillation. The oscillation time is determined by the delay module M4 and the pulse module M5. The time period is 20 seconds. When the oscillation time is over, the memory generator module M3 is reset and the pulse oscillation output The superposition amount is set by the set value module M6, and the set value is equal to 3%. The adder module M7 is introduced to superimpose the command output signal of the cone valve as a new command output signal of pulse oscillation, and the switching terminal of the switching module M8 Realize a period of pulse oscillation.

When a period of conical valve pulse oscillation ends, if the deviation between the input command signal P of the conical valve electric control baffle and the output signal of the conical valve opening position sensor M9 is within the dead zone range, the conical valve will The opening electronic control unit does not perform pulse oscillation output, maintains the existing opening, and avoids frequent oscillation of the cone valve; When the deviation is outside the dead zone range, the electronic control adjustment system will continue to perform pulse oscillation.

The invention adopts a set value module, a switch module, an adder module, a subtractor module, a memory generator module, a delay module, a pulse module and a dead zone module in the distributed control system. In order to prevent the cone valve from being blocked by dust particles, the valve position of the cone valve cannot always be kept at the same position. On the basis of the output, the appropriate offset and pulse control are superimposed as the final valve oscillation output. At the same time, when the deviation between the cone valve opening command and the position feedback is within the dead zone, the control system does not perform pulse oscillation output and maintains The existing opening avoids frequent oscillation of the cone valve.

Claims (2)

1. the automatically controlled regulating system of External Heat Exchanger in CFB Boiler mitre velve, comprises mitre velve valve opening position transducer (M9), setting value module (M6), handover module (M8), adder Module (M7), subtracter block (M1), memory generator module (M3), time delay module (M4), pulse module (M5), dead band module (M2); It is characterized in that, the output terminal of mitre velve valve opening position transducer (M9) and the first input end (i of subtracter block (M1) ₁) link together, the second input end (i of the automatically controlled baffle plate input instruction signal (P) of mitre velve and subtracter block (M1) ₂) link together, the output terminal (O of subtracter block (M1) ₁) with the input end (i of dead band module (M2) ₃) link together, the output terminal (O of dead band module (M2) ₂) input set end (S) link together with first of memory generator module (M3), remember the output terminal (O of generator module (M3) ₃) with the input end (i of time delay module (M4) ₄) link together, the output terminal (O of time delay module (M4) ₄) with the input end (i of pulse module (M5) ₅) link together, the output terminal (O of pulse module (M5) ₅) input reset terminal (R) and link together with second of memory generator module (M3), the output terminal (O of setting value module (M6) ₆) with the first input end (i of adder Module (M7) ₆) link together, the second input end (i of the automatically controlled baffle plate input instruction signal (P) of mitre velve and adder Module (M7) ₇) link together, the output terminal (O of adder Module (M7) ₇) with the first input end (i of handover module (M8) ₈) link together, the second input end (i of the automatically controlled baffle plate input instruction signal (P) of mitre velve and handover module (M8) ₉) link together, the output terminal (O of memory generator module (M3) ₃) with the switch terminal (S of handover module (M8) ₁) link together, the output terminal (O of handover module (M8) ₈) link together with mitre velve valve opening ECU (Electrical Control Unit).

2. the automatically controlled regulating system of a kind of External Heat Exchanger in CFB Boiler mitre velve according to claim 1, it is characterized in that, dead band module (M2) to be dead band definite value be 2% dead band module, when dead band is greater than 2%, it is 1 that dead band module exports, when dead band is less than 2%, it is 0 that dead band module exports; Setting value module (M6) to be setting value be 3% setting value module.