JPS599690Y2 - Temperature control device for denitrification reactor - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a temperature control device for a denitrification reactor.

This was done by cutting the economizer tube to increase the gas temperature at the outlet of the economizer, thereby reducing the absorption of boiler exhaust gas in the economizer.

However, when using such a method, the efficiency of the boiler decreases and the cost of tube cutting increases, resulting in a significant increase in the cost of obtaining high-temperature gas.

Therefore, in a denitrification reactor, it is an absolute condition that the catalyst installed in the reactor be heated to a specified temperature or higher.

From this point of view, the present invention has discovered a temperature control device that can reduce the cost of modification work without reducing boiler efficiency. When supplying the denitrification reactor together with ammonia gas, a carbon-saving bypass circuit is provided between the superheater and the boiler economizer and between the economizer outlet damper and the reactor, and the economizer outlet damper is connected to an air flow rate transmitter. The economizer bypass damper is controlled by the output signal of the function generator which inputs the output of the air flow transmitter and outputs the reactor inlet gas temperature signal and the reactor. It is characterized in that it is controlled by the output signal of the PI controller which receives as input the deviation signal from the output signal of the inlet gas temperature measuring device.

In other words, the device of the present invention sequentially introduces the high temperature combustion gas discharged from the boiler into the superheater and the economizer, utilizes this high temperature, and then maintains the high temperature before introducing it into the denitrification reactor. .

An embodiment of the present invention will be described in detail based on the drawings.

As shown in FIG. 1, a main duct is used to introduce the combustion gas that has passed through the boiler superheater 1 into the boiler economizer 2 and send it into the reactor 3 via the outlet damper 4 of the economizer. A and the main duct are provided with an energy saver bypass duct B.

This bypass duct consists of superheater 1, economizer 2, and economizer 2.
and the reactor 3.

Also, ammonia gas is injected between the intersection of the main duct and the pass duct and the reactor inlet temperature transmitter 7.

In addition, 5 is the economizer bypass damper, 6 is the inlet temperature transmitter of the economizer, 8 is the economizer inlet draft, 9 is the lung carbonizer output damper outlet draft, and 10 is the economizer bypass damper output draft. .

Also, the control mechanism in the device of the present invention will be explained.

In Fig. 2, 11 is an air flow rate (load) transmitter, 12
is the draft program (function generator) for loading
, 13 and 22 are automatic/manual switching stations, 14 and 23 are voltage/current converters, 15 and 24 are current/air converters, 16 is an economizer output damper, 17 and 28 are manual open/close signal operation switches, 18 .29 and 31 are analog memories, 19 is a reactor inlet temperature measuring device, 20 is a deviation device,
21 is a PI controller (proportional integral controller), 25 is a power saving bypass damper, 26 is a temperature program for the load, 27 is an adder, and 30 is a manual bias signal operation switch.

(I) Regarding draft control (B) In the case of automatic mode, the temperature can be controlled by the air flow signal 11 via the function generator 12 and the opening adjustment device 25.25 of the economizer bypass damper 5. The opening degree of 4 is set and the valve is operated only by a command signal.

(b) In the case of manual operation, the automatic/manual switching station 13 allows the automatic/manual switching station 13 to remotely control the output of the energy saver and the damper 4. It is operated by setting the opening degree.

(II) Regarding temperature control (a) In the case of automatic mode, the air flow signal 11 is used to program the function generator 26 so that the reactor gas temperature becomes a predetermined temperature for the load. This signal is called a set value, and the set value and measured value (reactor inlet gas temperature detected by thermocouple) are compared, and the PI regulator 21 opens the energy saver bypass damper so that the temperature reaches the set value. Decide on the degree.

Furthermore, if it is desired to apply a bias to the set temperature, the manual bias setting devices 30 and 31 can also apply the bias.

An example of the operating procedure is shown in Fig. 3, in which the opening degrees of the economizer bypass damper and the economizer outlet damper are adjusted so that the reactor inlet gas temperature becomes the temperature shown in graph A in the figure. If it is automatic as shown in Figure 3 B and C, it will be adjusted automatically.
If the operation is manual, perform the manual operation so as not to cause any disturbance to the operating state of the boiler.

Note that the point X in the figure differs depending on the boiler and catalyst.

Note that the air flow rate and the draft of each part of the boiler differ depending on the load, and the air flow rate changes approximately proportionally if the load is 30% MCR (maximum continuous load) or more.

In this way, by making the pressure loss of the gas passing through the main duct larger than the pressure loss of the gas passing through the bypass duct in the outlet damper 4 of the economizer, the high temperature gas 6 at the inlet of the economizer is sent through the bypass damper 5 to save energy. This allows gas to flow into the reactor bypass side, and gas that is not absorbed by the gas temperature by the economizer can flow into the reactor, preventing deterioration of the catalyst installed in the reactor due to a drop in temperature. can.

According to the device of the present invention, the role of each control system can be simplified.

In other words, the economizer output rod damper controls the economizer outlet draft, and the economizer bypass damper controls the temperature at the reactor inlet, and since any control system loop can be set up before this, mutual interference can be reduced. I can do it.

Therefore, if the draft and temperature regulators are adjusted to reduce sudden changes in the draft at the reactor inlet, disturbances to the furnace pressure control (in the case of a balanced draft boiler) and air flow rate control due to sudden changes in the draft as a boiler system can be avoided. can be suppressed as much as possible.

As detailed above, according to the device of the present invention, a circuit of the economizer bypass damper is provided, and the high temperature gas is bypassed by throttling the economizer output damper so that the resistance on the bypass line side is smaller than that on the main datsupa side. Since it is made to flow through the line side, it has remarkable effects such as being able to introduce high temperature boiler exhaust gas into the reactor without reducing the efficiency of the boiler.

[Brief explanation of the drawing]

Fig. 1 is a conceptual explanatory diagram showing the mechanism of the device of the present invention, Fig. 2 is a schematic explanatory diagram showing the mechanism of the main part of the device of the present invention, and Fig. 3 is a diagram showing the opening/closing degree of the damper and the gas temperature in the device of the present invention. It is a relationship curve diagram. 1... Boiler superheater, 2... Boiler economizer, 3... Reactor, 4... Coal economizer output rod damper, 5... ... Economizer bypass damper,
6... Economizer inlet temperature transmitter, 7...
Reactor inlet temperature transmitter, 8... Economizer inlet draft, 9... Economizer output rod damper output rod draft I.
, 10... Economizer bypass damper output draft, 11... Air flow rate transmitter, 16...
Energy saving device bypass damper 25... Energy saving device bypass damper

Claims (1)

[Scope of utility model registration request] When the combustion exhaust gas that has passed through the superheater is supplied to the denitrification reactor together with ammonia gas through the economizer and the coal-saving damper, there are A circuit for a coal burner bypass damper is provided, and the economizer output damper is controlled by the output signal of a function generator which uses the output of the air flow transmitter as a human power, and the economizer bypass damper is controlled by the output signal of a function generator that uses the output of the air flow transmitter as a human power. The denitrification is controlled by the output signal of a PI controller which receives as input the deviation signal between the signal of a function generator which inputs and outputs a reactor inlet gas temperature signal and the output signal of a reactor inlet gas temperature measuring device. Temperature control device for reactor.