JP2001272022A - Method for controlling operation for exhaust gas treatment and exhaust gas treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method by which an exhaust gas treatment system which treats the gas produced when wastes and fuel are burnt and melted is controlled so that the internal pressure of the system may not become an excessively low negative pressure even when the stages of treatment facilities increases. SOLUTION: The pressure in the exhaust gas treatment system is prevented from becoming the excessively low negative pressure by setting up an induced draft fan which adjusts the internal pressure of the system in the system in addition to another induced draft fan which forcibly discharges the exhaust gas and controlling the operations of the fans. When the induced draft fan on the inlet side of the system is controlled through dampers and the induced draft fan on the outlet side of the system is subjected to VVVF control, a change in operating pattern can be coped with easily. The number of the induced draft fans, in addition, can be changed in accordance with the number of treatment stages in the system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas treatment system for treating combustion gas from an incinerator that incinerates or melts waste or fuel and discharges it as exhaust gas into the atmosphere, and an operation control method thereof. About.

[0002]

2. Description of the Related Art In recent years, the generation and effects of various harmful substances generated during the disposal of waste have become a major social problem. In particular, in an exhaust gas treatment system that emits exhaust gas into the atmosphere after incinerating and melting wastes and fuels, emission regulations for waste emission processing are becoming stricter. In order to respond to stricter emission regulations, waste treatment systems that treat waste, especially exhaust gas treatment systems, require processing equipment that can handle regulated waste.
Facilities have been added. For this reason, the exhaust gas treatment system tends to be complicated and large in size.

[0003] On the other hand, since the waste itself treated by the exhaust gas treatment system is also becoming diversified and complicated, it is required that a system for treating these wastes performs a treatment suitable for each waste. This means that in the case of the exhaust gas treatment system, it is necessary to perform operation control according to the waste to be regulated and treated, and to set each waste to a value conforming to the regulation.

As a large and complicated exhaust gas treatment system, a plurality of stages of treatment equipment such as a filter, a denitration tower, and an exhaust gas washing tower are connected in series by piping between an incinerator and a discharge section such as a chimney. An exhaust gas treatment system has been proposed. This exhaust gas treatment system can not only remove harmful nitrogen compounds and the like, but also prevent emission of dioxins and the like. In the case of the proposed exhaust gas treatment system, an operation method is employed in which the residual gas subjected to the exhaust gas treatment is directly sent to a discharge section such as a chimney by a ventilator and is forcibly released into the atmosphere.

[0005]

However, in the case of using this operating method, as the number of stages of the processing equipment in the exhaust gas processing system increases in accordance with the control target and the size of each processing equipment increases. The more you go, the more filters,
It has been found that the durability of processing equipment such as a denitration tower and an exhaust gas cleaning tower is low and the life is short.

SUMMARY OF THE INVENTION An object of the present invention is to provide an operation control method of an exhaust gas treatment system that can cope with an increase in the number of stages of the treatment equipment and an increase in the size of the treatment equipment in the exhaust gas treatment system.

Another object of the present invention is to increase the complexity of processing equipment,
Another object of the present invention is to provide an operation control method that can maintain the durability even when the size is increased, and can operate stably for a long period of time.

It is still another object of the present invention to provide an exhaust gas treatment system capable of performing an operation suitable for a treatment facility.

[0009]

According to one aspect of the present invention, there is provided an operation control method for use in an exhaust gas treatment system for forcibly releasing residual gas subjected to exhaust gas treatment to the atmosphere. There is provided an operation control method for exhaust gas treatment, characterized in that the internal pressures of a plurality of constituent equipment are controlled so as to approach the atmospheric pressure, and the influence of the atmospheric pressure on the equipment is reduced.

According to another aspect of the present invention, an exhaust gas treatment system connected between a combustion furnace and a discharge section for treating combustion gas from the combustion furnace with the exhaust gas and forcibly releasing the exhaust gas to the atmosphere through the discharge section. In the system, a filter for removing dust from the combustion gas, and a plurality of removal equipment connected in series between the filter and the emission unit to remove harmful substances other than dust, further comprising: Between the filter and the first stage of the removal equipment, and between the last stage of the removal equipment and the discharge unit, having a ventilation control means for controlling the internal pressure in the plurality of removal equipment. The characteristic exhaust gas treatment system is obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, an exhaust gas treatment system according to an embodiment of the present invention will be described. In the illustrated exhaust gas treatment system, the combustion gas is cooled from a combustion furnace section 10 constituted by a rotary kiln or the like, and then sent through a pipe. In this cooled gas, solid dust, nitrogen compounds,
Hazardous substances such as sulfur compounds and hydrogen chloride are contained, and the exhaust gas treatment system prevents these harmful substances from being directly discharged into the atmosphere by removing these harmful substances.

The exhaust gas treatment system shown in FIG. 1 has a bag filter section 1 for removing dust such as dust by filtering.
1. A denitration tower section 12 for removing nitrogen compounds in combustion gas and a washing tower section 13 for neutralizing and removing hydrogen chloride, sulfur compounds and the like are provided as processing equipment. Among them, the bag filter section 11 filters dust using a filter cloth in the gas sent from the combustion furnace section 11 to separate the dust. The dust adsorbed on the filter cloth is discharged to the outside as needed.

The illustrated denitration tower section 12 and exhaust gas washing tower section 13 are provided with bypass pipes, respectively, and are selectively provided with the devices 12, 13 according to the properties of the exhaust gas.
May be bypassed. That is, nitrogen compounds (NOx)
When the amount of generation of methane is small, the denitration tower section 12 may be bypassed, and in the case of low chlorine, the cleaning tower section 13 may be bypassed. Although not shown, a switching valve is provided at a connection between the main duct of each of the devices 12 and 13 and the bypass pipe.

In the exhaust gas treatment system shown in FIG. 1, an induction ventilator 14 is provided at the outlet side of the washing tower section 13, and the gas pushed in from the combustion furnace 10 by the induction ventilator 14 is attracted. The pressure in the exhaust gas treatment system is kept constant, and the induced exhaust gas is released into the atmosphere from a chimney 15 as a discharge unit. Here, it can be seen that the exhaust gas treatment system employs the balanced ventilation system.

However, in the operation method in which the gas pressure in the exhaust gas treatment system is controlled only by the single induction ventilator 14, compared with the atmospheric pressure, the denitration tower unit 12 and the cleaning tower unit 13
It was confirmed that a state in which the internal pressure was low, that is, a negative pressure state occurred. Specifically, when the gas of the exhaust gas treatment system is induced by a single induction ventilator 14 and led to a chimney or the like, as is clear from the broken lines in FIG. The pressure in the exhaust gas treatment system from the bag filter 11 to the cleaning tower 13 via the denitration tower 12 increases as the pressure approaches the cleaning tower 13. This negative pressure state is applied to the washing tower 1
It turned out to be the largest at the exit side of No. 3 and could reach -4 to -5 kPa. In addition, it is confirmed that as the number of stages of the processing equipment such as the denitration tower unit 12 and the washing tower unit 13 increases according to the waste to be treated, the pressure loss increases and the negative pressure increases. It was confirmed that the load on the machine 14 also increased.

As described above, when the exhaust gas treatment system is operated in the negative pressure state, the denitration tower section 12 and the cleaning tower section 13 need to have a structure capable of withstanding the negative pressure state. Therefore, the design specifications of the equipment and the like used in the denitration tower section 12 and the washing tower section 13 must also have a structure that can withstand a large negative pressure. For this reason, it is necessary to use a large and strong device capable of withstanding a negative pressure as the denitration tower unit 12, the washing tower unit 13, and the equipment used for them.

In consideration of the above points, in the exhaust gas treatment system according to one embodiment of the present invention, the gas from the combustion furnace 10 or the like is induced by a plurality of induction ventilators, and the negative gas in the exhaust gas treatment system is reduced. Operation control is performed to reduce the pressure and approach the atmospheric pressure. More specifically, in the exhaust gas treatment system shown in FIG. 1, in addition to the induction ventilator 14 connected to the chimney 15, the induction ventilator 16 is also provided between the bag filter 11 and the denitration tower unit 12. Is provided. As described above, the illustrated exhaust gas treatment system includes the bag filter unit 11,
Induction ventilator 16, denitration tower section 12, washing tower section 13, and
A structure is provided in which the induction ventilators 14 are connected in series with each other by piping.

As described above, the plurality of induction ventilators 14 and 1
In the case of an exhaust gas treatment system that controls the ventilation state by the induction ventilators 14 and 16, a pressure distribution state as shown by a solid line in FIG. 2 was obtained.

As is clear from the solid line in FIG. 2, by installing the induction ventilator 16 at the subsequent stage of the bag filter section 11, the negative pressure state in the bag filter section 11 is once brought to a state close to the atmospheric pressure. And the negative pressure state in the denitration tower section 12 and the washing tower section 13 located at the subsequent stage of the induction ventilator 16 is also greatly improved. As described above, in the present embodiment, a plurality of the induction ventilators 14 and 16 are provided, and the role of each of the induction ventilators 14 and 16 is shared. System can be configured. In other words, a plurality of induction ventilators 1
The exhaust gas treatment system can be operated at an appropriate operating point by providing the air blowers 4 and 16 and individually controlling each of the induction ventilators 14 and 16.

Further, by controlling the plurality of induction ventilators 14 and 16 with damper control and VVVF control, the efficiency of the equipment can be improved and safe operation can be ensured. In particular, if the pressure of the induction ventilator 16 is damper-controlled by the inlet damper on the combustion furnace 10 side, and the exhaust gas equipment pressure located at the subsequent stage is VVVF-controlled by the subsequent induction ventilator 14,
It is possible to cope with many operation patterns and to perform operation by balanced ventilation control.

In the above-described embodiment, the induction ventilator is
Although only the case where one is installed is described, the present invention is not limited to this, and more induced drafters may be installed in the exhaust gas treatment system. For example, an induction ventilator may be provided between the denitration tower section 12 and the washing tower section 13, and furthermore, the number of induction ventilators increases with an increase in the number of processing equipment such as the denitration tower section 12. You may let it. In any case, the present invention only needs to be able to adjust the pressure in the processing equipment so that the negative pressure applied to the processing equipment approaches the atmospheric pressure.

[0022]

As described above, according to the present invention,
When the equipment is changed, it is possible to easily cope with reducing the negative pressure state by changing the operation pattern of the plurality of induction ventilators, and therefore, control is performed so that no extra negative pressure is applied to the exhaust gas treatment equipment. An operating method for exhaust gas treatment that can be performed is obtained. According to this method, it is possible to prevent the induction ventilator from increasing in size as the exhaust gas treatment equipment becomes more complicated and larger, while also avoiding an excessive negative pressure operation at the inlet of the induction ventilator. For this reason, there is an effect that the design specification of the equipment constituting the exhaust gas treatment system can be simplified and the equipment can be operated stably for a long period of time.

Further, according to the present invention, it is possible to prevent an increase in the size of the induction ventilator when one induction ventilator is used and to prevent deviation from the optimal operation point of the induction ventilator in each operation pattern.

[Brief description of the drawings]

FIG. 1 is a system block diagram for explaining an exhaust gas treatment system according to one embodiment of the present invention.

FIG. 2 is a pressure distribution diagram showing an internal pressure in a portion corresponding to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Incinerator 11 Bag filter part 12 Denitration tower part 13 Cleaning tower part 14 Induction fan 15 Chimney 16 Induction fan

Claims (6)

[Claims] 1. An operation control method used in an exhaust gas treatment system for forcibly releasing residual gas subjected to exhaust gas treatment to the atmosphere, wherein an internal pressure of a plurality of facilities constituting the exhaust gas treatment system approaches an atmospheric pressure. And controlling the influence of the atmospheric pressure on the equipment. 2. The exhaust gas treatment system according to claim 1, wherein the exhaust gas treatment system includes a plurality of facilities connected in series via a pipe between a combustion furnace and a discharge unit, and a plurality of facilities between the plurality of facilities. An operation control method for exhaust gas treatment, wherein a plurality of ventilation control means for reducing the influence of the atmospheric pressure on the facility are provided at a location. 3. The exhaust gas treatment operation control method according to claim 2, wherein each of the plurality of ventilation control units is a ventilation fan. 4. The apparatus according to claim 3, wherein the plurality of facilities connected in series include a filter for removing dust from combustion gas from the combustion furnace, and a series connection between the filter and the discharge unit. And a plurality of stages of removing equipment for removing harmful substances other than dust, wherein the ventilator is provided between the filter and the first stage of the removing unit, and the final stage of the removing unit and the discharge unit. An operation control method for exhaust gas treatment, which is provided between them. 5. An exhaust gas treatment system that is connected between a combustion furnace and a discharge section for exhaustly treating combustion gas from the combustion furnace and forcibly releasing the gas through the discharge section to the atmosphere. And a filter that is connected in series between the filter and the discharge unit and includes a plurality of stages of removal equipment that removes harmful substances other than dust, and further includes a first stage of the filter and the removal equipment. An exhaust gas treatment system comprising ventilation control means for controlling internal pressure in the plurality of stages of removal equipment between the discharge equipment and the final stage of the removal equipment and the discharge section. 6. An exhaust gas treatment system according to claim 5, wherein said ventilation control means is an induction ventilator.