KR101165646B1 - Energy reducing system of nox reducing apparatus using waste-heat and steam type gas heater - Google Patents

Abstract

PURPOSE: The energy saving system of a nitrogen oxide reducing apparatus using waste heat and a vapor type gas heater is provided to increase the using efficiency of energy by preventing the re-exchange of heat between high temperature flue gas and saturated liquid. CONSTITUTION: The energy saving system of a nitrogen oxide reducing apparatus includes a bag filter(105), a steam header(140), a vapor type gas heater(110), a duct burner(115), a selective catalytic reaction column(120), and an induced blower(125)/chimney(130). The bag filter eliminates dust from flue gas generated from the incineration of waste and discharges cooled flue gas without the dust. The steam header collects waste heat form the incineration of the waste and stores the waste heat as steam of 190 degrees Celsius or more. The vapor type heater heat-exchanges the flue gas form the bag filter based on the steam. The duct burner heats the flue gas using auxiliary fuel according to the temperature of the flue gas. The selective catalytic reaction column eliminates nitrogen oxide from the flue gas discharged from the duct burner. The induced blower/chimney discharges the flue gas form the selective catalytic reaction column to atmosphere.

Description

ENERGY REDUCING SYSTEM OF NOx REDUCING APPARATUS USING WASTE-HEAT AND STEAM TYPE GAS HEATER}

The present invention relates to an energy saving system of a nitrogen oxide reduction apparatus using waste heat and a steam gas heater, and more particularly, energy for reducing energy to be used in a device for removing nitrogen oxides from exhaust gases generated during waste incineration. It is about a reduction system.

In general, nitrogen oxides (NOx) refer to air pollutants generated by oxidation of nitrogen in the air during waste incineration. Such nitrogen oxides have been generated not only in incinerators but also in the overall industry, such as automobiles, aircraft, and industrial boilers.

However, nitrogen oxides are not only a cause of acid rain, but also harmful to the human body, and cause acute poisoning of respiratory diseases such as pulmonary edema and bronchitis.

Accordingly, the World Environmental Organization recognizes nitrogen oxides as harmful substances and regulates the emission of nitrogen oxides below the regulatory level. Various industries and research institutes are actively developing technologies to minimize the concentration of nitrogen oxides emitted into the atmosphere. It's happening.

As a representative example, there is an energy saving system for nitrogen oxide using a selective catalytic reduction (SCR). The selective catalytic reduction method applied to the nitrogen oxide reduction system reduces the nitrogen oxides to nitrogen gas by the reaction as shown in the following formula (1) while the exhaust gas passes through the catalyst layer.

4NO + 4NH ₃ + O ₂ ---> 4N ₂ + 6H ₂ O

2N0 ₂ + 4NH ₃ + O ₂ ---> 3N ₂ + 6H ₂ O (Equation 1)

Such selective catalytic reduction is affected by temperature, which should be at least 200 ° C. in the activity and selectivity of the catalyst. However, since the exhaust gas generated from the combustion furnace is rapidly dropped to approximately 150 ° C or lower through a prevention device for removing air pollutants, fuel such as LNG or bunker oil for raising the temperature of the exhaust gas to 200 ° C or higher. Was used.

The use of such a fuel provided a cause for increasing energy consumption, and ultimately, there was a problem in that the use efficiency of energy used in the nitrogen oxide incineration process was greatly reduced.

The present invention has been made to solve the above problems, an object of the present invention is to minimize the amount of auxiliary fuel used in the duct burner, to reduce the energy to be used in the device for removing nitrogen oxides in the exhaust gas generated during waste incineration The present invention aims to provide an energy saving system of a nitrogen oxide reduction device that can increase energy use efficiency.

In order to accomplish the objects of the present invention as described above and to carry out the characteristic functions of the present invention described below, features of the present invention are as follows.

According to an embodiment of the present invention, after removing the dust of the exhaust gas with respect to the exhaust gas generated during waste incineration, the bag filter for discharging the exhaust gas dropped to 150 ℃ or less; A steam header for recovering waste heat generated during incineration of the waste and storing the waste heat as steam of 190 ° C. or higher; A steam-type gas heater that heat-exchanges the exhaust gas discharged from the bag filter within a range of 180 ° C. to 200 ° C. by using steam stored in the steam header; A duct burner for heating to 200 ° C. or more using auxiliary fuel when the temperature of the exhaust gas discharged from the steam gas heater is 200 ° C. or less; A selective catalytic reaction tower for removing nitrogen oxides from the exhaust gas discharged from the duct burner; Provided is an energy saving system of a nitrogen oxide reduction device comprising a; and a manned blower / stack to inject the exhaust gas discharged from the selective catalytic reaction tower to discharge into the atmosphere.

Here, the steam gas heater according to an embodiment of the present invention, the heat exchange with the exhaust gas by using the latent heat generated when the steam is supplied in the state of saturated steam or superheated steam and the phase change to a saturated liquid state At least two or more may be provided, and each of the saturated steam or superheated steam may be introduced into a saturated liquid state and discharged.

In addition, the steam gas heater according to an embodiment of the present invention, it is preferably made of three stages, the exhaust gas discharged from the bag filter through the upper portion of the steam gas heater of the first stage of the three stages By pulling in, heat may be exchanged with latent heat generated in the steam gas heaters of each stage and discharged to the bottom of the steam gas heaters of the third stage of the three stages.

In addition, the energy saving system of the nitrogen oxide reduction device according to an embodiment of the present invention is supplied with a saturated liquid state discharged from the at least two or more steam gas heaters to coexist with the steam to separate into a gas and a liquid And a degassing unit for discharging only liquid in the gas and the liquid that have passed through the plurality of traps.

In addition, each of the steam-type gas heater according to an embodiment of the present invention, the plurality of welded or bent (bending) to the phase change to the saturated liquid state by respectively entering the saturated steam or superheated steam state U-tubes may be provided.

In addition, the milk tube tube for introducing the saturated steam or superheated steam state of the plurality of milk tube tubes according to an embodiment of the present invention is made of a material exhibiting elasticity in response to thermal expansion by the saturated steam or superheated steam state The remaining tube tube may be made of a material different from the above material. At this time, the tube tube for introducing the saturated steam or superheated steam state is made of STS 316L, the remaining tube tube is preferably made of STBH 340.

According to the present invention, a steam header and a steam gas heater utilizing waste heat are provided before the selective catalytic reaction tower, and the temperature of the exhaust gas is increased, thereby reducing nitrogen oxide and greatly reducing the amount of auxiliary fuel used. This has the effect of increasing the use efficiency of energy.

In particular, at least two or more steam gas heaters are provided, and each stage allows heat exchange between the hot exhaust gas and the saturated gas or between the exhaust gas and the superheated gas, thereby providing a single steam gas heater. It is possible to prevent the re-heat exchange between the high-temperature exhaust gas and the saturated liquid caused by the high efficiency of the use of energy.

In addition, according to the present invention, a plurality of u-tubes (u-tube) disposed in each steam gas heater is provided, so that the phase change of the saturated steam or superheated steam caused by waste heat to the saturated liquid state is easy. By doing so, there is an effect that can be utilized to heat exchange the latent heat generated therein.

In addition, according to the present invention, since a plurality of u-tubes welded and bent are provided, elasticity can be exerted in response to thermal expansion due to saturated steam or superheated steam, resulting in smooth saturation. Steam or superheated steam flow can be maintained, and in particular, it is made of a special material such as STS 316L has the effect of preventing corrosion by high temperature.

1 is a view showing an energy saving system 100 of the nitrogen oxide reduction device according to an embodiment of the present invention by way of example.
2 is a view schematically showing a steam gas heater 110 and its related configuration for treating steam according to an embodiment of the present invention.
3 is a view showing in more detail the structure of the steam gas heater 110 according to an embodiment of the present invention.
Figure 4 is a view showing in more detail the oil tube tube 114 provided in each steam gas heater 110 according to an embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

Example of energy saving system

1 is a view showing an energy saving system 100 of the nitrogen oxide reduction device according to an embodiment of the present invention by way of example.

As shown in Figure 1, the energy saving system 100 of the nitrogen oxide reduction device according to an embodiment of the present invention is a bag filter 105, steam header 140, steam gas heater 110, duct It includes a burner 115, a selective catalytic reaction tower 120, a manned blower 125 / stack 130, a degasser 145 and an air blower 135.

First, the bag filter 105 according to the present invention serves to remove the dust of the exhaust gas with respect to the exhaust gas generated during waste incineration, and then discharge the exhaust gas from which the dust has been removed. At this time, the exhaust gas is discharged to a temperature of less than 150 ℃, more precisely 140 ℃ ~ 150 ℃ when passing through the boiler (not shown), semi-dry reaction tower (not shown) and the bag filter 105 of the previous step Has

Therefore, it is necessary to raise the temperature of the exhaust gas which fell by the bag filter 105 to 200 degreeC which is a suitable temperature at the time of selective catalyst reduction. To this end, the exhaust gas discharged by the bag filter 105 is supplied to the steam gas heater (110).

 Next, the steam header 140 according to the present invention recovers the waste heat generated during waste incineration and stores it as steam, which is thermal energy. At this time, the steam stored by the waste heat is maintained at 190 ℃ or more. As described above, the steam of 190 ° C. or higher is appropriately controlled to supply the steam gas heater 110 by controlling the steam pressure and the supply amount.

Next, the steam gas heater 110 according to the present invention is supplied with steam by waste heat from the steam header 140, and the exhaust gas is separated from the bag filter 105 to 150 ° C or less. When the exhaust gas and the steam is supplied, the steam gas heater 110 of the present invention heats up (heats) the exhaust gas dropped to 150 ° C. or lower within the range of 180 ° C. to 200 ° C. by using steam generated by waste heat. Is carried out.

When the steam and the exhaust gas by waste heat exchange heat, the temperature of the exhaust gas is raised within the range of 180 ° C to 200 ° C. The raised exhaust gas is supplied to the duct burner 115.

Here, the principle of raising the exhaust gas in the 180 ° C to 200 ° C range by the steam gas heater 110 will be described in detail later with reference to FIGS. 2 to 4.

On the other hand, since the steam-type gas heater 110 according to the present invention receives the steam by the waste heat from the steam header 140 in a saturated gas or superheated gas state, the saturated gas or superheated gas state is changed into a saturated liquid state. Drain the saturated liquid to the other outlet. In this case, the latent heat generated when the saturated gas or superheated gas is changed into the saturated liquid state is substantially heat-exchanged with the exhaust gas. The saturated liquid state generated after the phase change is sent to the deaerator 145. The principle of this phase change will be described later in more detail with reference to FIG. 3.

Next, the duct burner 115 according to the present invention serves to heat the exhaust gas supplied from the steam gas heater 110 to 200 ° C or more by using an auxiliary fuel such as LNG. When the temperature of the exhaust gas passing through the steam gas heater 110 is less than 200 ° C. according to the supplied steam temperature condition, the auxiliary fuel may be raised to an appropriate temperature of 200 ° C. or more, which is required for selective catalytic reduction by the auxiliary fuel.

As such, the auxiliary fuel which helps to heat the exhaust gas of 200 ° C or more is not necessary for the auxiliary fuel temperature depending on the supplied steam temperature conditions because the fuel is required to raise the exhaust gas temperature of approximately 20 ° C to 10 ° C. It can be reduced to about half the amount of auxiliary fuel used, which can reduce energy use by about half. The exhaust gas raised to 200 ° C. or more is supplied to the lower portion of the selective catalytic reaction tower 120.

Next, the selective catalytic reaction tower 120 according to the present invention serves to reduce the nitrogen oxide to nitrogen gas while passing through the catalyst layer by introducing the exhaust gas raised to 200 ° C or more supplied from the duct burner 115. In this case, the selective catalytic reduction (SCR) is applied. However, if it is determined that the reduction of nitrogen oxides to nitrogen gas is required for the exhaust gas of 200 ° C. or more, various methods can be applied without being limited to the selective catalytic reduction method. For example, a method such as non-selective catalytic reduction can be applied.

Next, the manned blower 125 according to the present invention is to remove the nitrogen oxide in the selective catalytic reaction tower 120 to introduce the exhaust gas discharged to the exhaust gas introduced from the stack 130 to the atmosphere. Finally, the degasser 145 serves to discharge the saturated liquid state sent from the steam gas heater 110, the discharged saturated liquid is sent to the boiler to be used. On the other hand, the air blower 135 serves to inject air into the duct burner (115).

As such, the exhaust gas is preheated by the steam gas heater 110 and treated in the selective catalytic reaction tower 120, so that nitrogen oxides in the exhaust gas can be efficiently removed, and preheated using waste heat generated during incineration. Therefore, the amount of energy used can be greatly reduced.

Hereinafter, the steam-type gas heater 110 in which heat exchange is performed using waste heat and another configuration related thereto will be described.

Steam gas heaters and their surrounding structures

2 is a view schematically showing a steam type gas heater 110 and its associated configuration for treating steam according to an embodiment of the present invention. 2, the energy saving system 100 of the nitrogen oxide reduction device according to the present invention, the supply line 160 is formed between the steam header 140 and the steam gas heater 110, at least two The steam gas heater 110 and the plurality of traps 155 formed between the steam gas heater 110 and the degasser 145 may be provided.

Here, the supply line 160 of the present invention is a steam-type gas heater to supply the steam by the waste heat discharged from the steam header 140 to each of the steam-type gas heater (110) consisting of at least two or more structures Supply lines 160 are provided as many as the number corresponding to 110. Preferably, the steam gas heater 110 may have a three-stage structure, and correspondingly, the supply line 160 may also be provided with three lines.

As such, the reason why the steam gas heaters 110 are provided in at least two or more, for example, three-stage structures is that steam of high temperature is introduced into the upper end of the steam gas heaters 110 and discharged from the lower end thereof. The superheated steam is discharged after a phase change to a saturated liquid state. When the inlet and discharge of steam are installed from the steam gas heater 110 to one supply line 160, the steam gas heater 110 is used. In order to prevent re-heat exchange between the hot exhaust gas and the saturated liquid at the lower end of the steam gas heater 110 and the supply line 160 is preferably provided in three stages (three lines).

When the three-stage steam gas heater 110 is provided, between the hot exhaust gas and the saturated gas in each steam gas heater 110 (saturated gas before the phase change from saturated gas to saturated liquid). Alternatively, heat exchange may be normally performed between the hot exhaust gas and the superheated gas (superheated gas before the phase change from the superheated gas to the saturated liquid).

Since each supply line 160 is connected to the corresponding steam gas heater 110, the steam is uniformly supplied to each steam gas heater 110 by the flow meter 150 or each steam gas heater 110 is connected to the corresponding steam gas heater 110. The gas heater 110 may supply steam unevenly as necessary. At this time, the steam supplied to each steam gas heater 110 is supplied in a saturated steam or superheated steam state of 190 ℃ or more.

Therefore, each vapor-type gas heater 110 according to the present invention is supplied in saturated steam or superheated steam state of 190 ° C. or higher, and is phase-changed and discharged into a saturated liquid state at the same temperature. Accordingly, each vapor-type gas heater 110 is used for heat exchange as described above by using latent heat according to the phase change. The saturated liquid state discharged from each steam gas heater 110 is supplied to a plurality of traps 155 corresponding to each steam gas heater 110.

The plurality of traps 155 according to the present invention are each supplied with a saturated liquid state discharged from at least two or more steam gas heaters 110, and the saturated liquid state coexists with steam. Therefore, steam is not discharged, only liquid flows, and the separated liquid is sent to one degasser 145. In this case, the deaerator 145 according to the present invention removes the dissolved oxygen in the liquid, and supplies the liquid from which the dissolved oxygen is removed to be used as water supply in a boiler (not shown). The presence of dissolved oxygen in the feed water causes corrosion of the feed water system, which leads to the hidden degradation of the piping system, so the deaerator 145 is essential in the boiler installation.

As such, when at least two or more, for example, three-stage steam gas heaters 110 are provided, the phase change of the saturated gas or superheated gas into a saturated liquid state and at the same time the latent heat generated at the time of the phase change is provided. Since the heat exchange can be performed effectively with the exhaust gas, the exhaust gas temperature can be increased within the range of 180 ° C to 200 ° C.

Steam Gas Heater Example

3 is a view showing in more detail the structure of the steam gas heater 110 according to an embodiment of the present invention. Referring to Figure 3, the steam gas heater 110 according to the present invention is at least two or more, preferably consisting of a three-stage (three) structure.

The steam gas heater 111 of the first stage receives the exhaust gas discharged from the bag filter 105 through the upper part and sends the exhaust gas to the lower part, and receives the steam on the left side and phase-changes the lower side of the same side to the lower side of the same side. It is structured to discharge. At this time, the plurality of duct tube (u-) interconnected to change the steam phosphorus saturated gas or superheated gas state into a saturated liquid state, and to effectively exchange heat with the exhaust gas flowing from the upper to the lower latent heat generated during the phase conversion. tube, 114).

The second stage steam gas heater 112 is provided with a plurality of u-tubes (u-tube, 114) to be discharged after the phase change by receiving steam, similar to the steam gas heater 111 of the first stage do. However, the second stage steam gas heater 112 receives the exhaust gas required for heat exchange from the first stage steam gas heater 111 and utilizes it during heat exchange, and then the third stage steam gas heater 113 is used. ).

The third stage steam gas heater 113 has a steam inlet and discharge structure similar to that of the first stage and second stage steam gas heaters 111, but from the second stage steam gas heater 112. After receiving the heat-exchanged exhaust gas and exchanging heat, it is discharged to the lower part. The exhaust gas discharged to the bottom is supplied to the duct burner 115 as described above in FIG. 1.

As such, the steam gas heater 110 according to the present invention introduces the exhaust gas discharged from the bag filter 105 through the upper portion of the first gas steam heater 111 of the three stages, thereby introducing the second stage. Between the exhaust gas passing through each stage in turn and the latent heat generated in each stage of the steam gas heater 110 while being supplied to the steam gas heater 112 and the steam gas heater 113 of the third stage. By having a structure in which heat exchange is carried out, the temperature of the exhaust gas can be increased within a range of 180 ° C to 200 ° C because heat exchange is smoothly performed between the exhaust gas and the saturated gas or between the exhaust gas and the superheated gas.

Example of You Tube

Figure 4 is a view showing in more detail the oil tube tube 114 provided in each steam gas heater 110 according to an embodiment of the present invention.

As shown in Figure 4, the oil tube tube 114 provided in the steam gas heater 110 according to the present invention is to change the saturated steam or superheated steam state to a saturated liquid state, so that the heat exchange is made In order to provide a plurality of 114.

The plurality of oil tube tubes 114 are welded and / or bent. For example, the tube tube 114c formed on the left side of the base of the reference 1 is welded to be connected in a 'U' shape, and the tube tube 114b formed on the right side of the base of the reference 2 is “U”. Bending treatment is carried out so as to form a magnetic shape. Bending treatment means that the bent shape is made using the maximum length of the manufacturable tube tube 114, and the welding treatment is a U tube having a U-shaped tube due to the length limitation of the tube tube 114. This means that the work required to connect the pipe (114).

Due to the plurality of the oil tube tube 114, the phase change of the saturated steam or superheated steam to a saturated liquid state is easily performed, and helps to generate latent heat, and thus it is possible to efficiently exchange heat with the exhaust gas.

On the other hand, the first tube tube 114a for introducing a saturated steam or superheated steam state of the plurality of tube tube 114 provided in each steam gas heater 110 is a saturated steam or superheated steam of 190 ℃ or more It is made of a material that can exert elasticity in response to thermal expansion due to saturated steam or superheated steam.

To this end, the tube tube 114a for introducing a saturated steam or superheated steam state is preferably made of STS 316L (Steel Type Stainless 316 Low Carbon). As such, if the tube tube 114a is made of STS 316L, corrosion due to inflow of saturated steam or superheated steam of 190 ° C. or higher may also be prevented.

On the other hand, the remaining tube tube (114b, 114c, 114d) is made of a different material in terms of cost efficiency compared to the first tube tube (114a). That is, it can be manufactured with STBH 340 (Carbon Steel Tubes for Boiler and Heat Exchanger), which is less sensitive to temperature and less flexible than the material of STS 316L.

However, the material is not limited to the above materials. For example, if the first tube tube 114a is capable of preventing corrosion in response to a high temperature and is adaptable to thermal expansion, it may be replaced with another material.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the exemplary embodiments or constructions. You can understand that you can do it. The embodiments described above are therefore to be considered in all respects as illustrative and not restrictive.

100: energy saving system 105: bag filter
110: steam gas heater 115: duct burner
120: selective catalytic reaction tower 125: manned blower
130: stack 135: air blower
140: steam header 145: deaerator
150: flow meter 155: trap
160: supply line 114: U tube

Claims (8)

A bag filter 105 for removing the dust of the exhaust gas with respect to the exhaust gas generated during waste incineration, and then discharging the exhaust gas dropped to 150 ° C or less;
A steam header 140 for recovering the waste heat generated during the incineration of the waste and storing the waste heat as steam of 190 ° C. or higher;
A steam gas heater (110) for heat-exchanging the exhaust gas discharged from the bag filter (105) using a steam stored in the steam header (140) within a range of 180 ° C to 200 ° C;
A duct burner 115 for heating to 200 ° C. or more using an auxiliary fuel when the temperature of the exhaust gas discharged from the steam gas heater 110 is 200 ° C. or less;
A selective catalytic reaction tower 120 for removing nitrogen oxides from the exhaust gas discharged from the duct burner 115; And
A manned blower (125) / binder (130) for introducing the exhaust gas discharged from the selective catalytic reaction tower (120) to discharge into the atmosphere;
Energy saving system of the nitrogen oxide reduction device comprising a. The method of claim 1,
The steam gas heater 110,
At least two or more steams are supplied in saturated steam or superheated steam state to exchange heat with the exhaust gas by using latent heat generated at the time of phase change to a saturated liquid state, and the saturated steam or superheated steam state is respectively drawn in. Phase change to a saturated liquid state to discharge each of the energy saving system of the nitrogen oxide reduction device. The method of claim 2,
A plurality of traps 155 for receiving a saturated liquid state discharged from the at least two or more steam gas heaters 110 and coexisting with the steam to separate the gas and the liquid;
And a degasser (145) for discharging only the liquid in the gas and the liquid that has passed through the plurality of traps (155). The method of claim 2,
The steam gas heater (110), the energy saving system of the nitrogen oxide reduction device, characterized in that consisting of three stages. The method of claim 4, wherein
The steam gas heater 110,
The latent heat generated in the steam type gas heater 110 of each stage by introducing the exhaust gas discharged from the bag filter 105 through the upper part of the first type of steam gas heater 111 of the three stages Heat exchange with the energy saving system of the nitrogen oxide reduction device, characterized in that for discharging to the lower portion of the third type of steam gas heater (113). The method of claim 4, wherein
Each of the steam gas heaters 110,
The nitrogen oxide, characterized in that it comprises a plurality of tube tube (u-tube, 114) welded or bending (bending) so that each of the saturated steam or the superheated steam is introduced into the saturated liquid state to the phase change to the saturated liquid state, respectively Energy saving system of abatement device. The method according to claim 6,
The tube tube 114a for introducing the saturated steam or superheated steam state among the plurality of tube tubes is made of a material that exhibits elasticity in response to thermal expansion due to the saturated steam or superheated steam state, and the other tube tube is Energy saving system of the nitrogen oxide reduction device, characterized in that made of a material different from the material. 8. The method of claim 7,
The tube tube (114a) for introducing the saturated steam or superheated steam state is made of STS 316L, the remaining tube tube is made of STBH 340, the energy saving system of the nitrogen oxide reduction device.

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