阅读说明：本技术 一种焦炉烟气脱硝及余热利用联合装置及利用其进行脱硝的方法 (Coke oven flue gas denitration and waste heat utilization combined device and method for denitration by using same ) 是由 李毛 张建国 王新义 吕有厂 曹德彧 周云辉 王军 李二军 畅宾平 高建伟 王育 于 2019-08-13 设计创作，主要内容包括：本申请公开了一种焦炉烟气脱硝及余热利用联合装置及利用其进行脱硝的方法,属于焦炉烟气脱硝技术领域,包括入口烟道、脱硝反应器和汽包,所述入口烟道设有烟气进口、氨气进口管道和三条烟气出口管道,每条烟气出口管道和脱硝反应器顶部对应的进口相连,脱硝反应器的下部壳体上设有净烟气出口,净烟气出口上方的脱硝反应器腔体内从上至下依次设有烟气均流构件、脱硝催化剂、蒸发换热器和预热换热器,蒸发换热器的进口和出口分别通过管线和汽包相连,预热蒸发器的进口连有软水管线,预热蒸发器的出口通过热水管线和汽包相连。利用本发明的装置,每年减排NOx2500吨,回收蒸汽每年10万吨,脱硝效率大于96%。(The application discloses coke oven flue gas denitration and waste heat utilization combined device and method for denitration by using the same, and belongs to the technical field of coke oven flue gas denitration, the device comprises an inlet flue, a denitration reactor and a steam drum, wherein the inlet flue is provided with a flue gas inlet, an ammonia gas inlet pipeline and three flue gas outlet pipelines, each flue gas outlet pipeline is connected with an inlet corresponding to the top of the denitration reactor, a clean flue gas outlet is formed in a lower shell of the denitration reactor, a flue gas flow equalizing component, a denitration catalyst, an evaporation heat exchanger and a preheating heat exchanger are sequentially arranged in a denitration reactor cavity above the clean flue gas outlet from top to bottom, the inlet and the outlet of the evaporation heat exchanger are respectively connected with the steam drum through pipelines, the inlet of the preheating evaporator is connected with a soft water pipeline, and the outlet of the preheating evaporator is connected with the steam drum through. By using the device, 2500 tons of NOx are reduced annually, 10 ten thousand tons of recovered steam are annually generated, and the denitration efficiency is more than 96%.)

1. The utility model provides a coke oven flue gas denitration and waste heat utilization combined device, includes entry flue, denitration reactor and steam pocket, its characterized in that, the entry flue is equipped with flue gas inlet, ammonia inlet pipe and three flue gas outlet pipe, every flue gas outlet pipe links to each other with the import that denitration reactor top corresponds, be equipped with clean flue gas export on the lower part casing of denitration reactor, be equipped with flue gas flow equalizing member, denitration catalyst, evaporation heat exchanger and preheating heat exchanger from last to having in proper order down in the denitration reactor cavity of clean flue gas export top, the import and the export of evaporation heat exchanger link to each other through pipeline and steam pocket respectively, the import of preheating evaporator even has soft water pipeline, the export of preheating evaporator links to each other through hot water pipeline and steam pocket, the steam pocket is equipped with steam output tube.

2. The coke oven flue gas denitration and waste heat utilization combined device as claimed in claim 1, wherein the inlet flue is S-shaped and is composed of an upper horizontal portion, a lower horizontal portion and a vertical portion connecting the upper horizontal portion and the lower horizontal portion, the left end inlet of the lower horizontal portion is a flue gas inlet, the right end branch of the upper horizontal portion is provided with three flue gas outlet pipelines, each flue gas outlet pipeline is provided with a gas burner, the gas burners are communicated with a gas pipeline, the top of the denitration reactor is provided with three inlets, the three flue gas outlet pipelines are respectively connected with the three inlets at the top of the denitration reactor, two partition plates are arranged in the cavity of the denitration reactor, and the partition plates extend upwards to the top of the cavity of the denitration reactor and downwards to the bottom of the denitration catalyst.

3. The coke oven flue gas denitration and waste heat utilization combined device as claimed in claim 2, wherein an ammonia gas mixing member is arranged below the vertical part of the inlet flue, the ammonia gas mixing member is connected with an ammonia gas inlet pipeline outside the inlet flue, the ammonia gas mixing member comprises an ammonia gas branch pipe, and a jet pipe is vertically arranged on the ammonia gas branch pipe.

4. The coke oven flue gas denitration and waste heat utilization combined device as claimed in claim 1, wherein the denitration catalyst is provided with three layers at intervals from top to bottom, the filling height of each layer is 1.0-1.8 m, and the distance between adjacent layers is 1.0-1.6 m.

5. The coke oven flue gas denitration and waste heat utilization combined device as claimed in claim 1, wherein the flue gas flow equalizing member is a perforated plate, the thickness of the perforated plate is 6mm to 20mm, the opening of the perforated plate is a square hole, a circular hole or a strip-shaped hole, and the flow area of the hole is one fourth to one third of the cross-sectional area of the denitration reactor.

6. The coke oven flue gas denitration and waste heat utilization combined device as claimed in claim 1, wherein the catalyst is a honeycomb catalyst, honeycomb holes are circular holes, square holes or hexagonal holes, the size of the honeycomb hole is 3-6 mm, and the honeycomb catalyst is a catalyst containing MoO₃V of₂O₅/TiO₂Catalyst and MoO₃In the mass of the catalyst is between 2.5 and 5 percent of the total mass of the catalyst, V₂O₅The mass of (A) is 1.5 to 3.0% of the total catalyst.

7. The coke oven flue gas denitration and waste heat utilization combined device as claimed in claim 1, wherein the evaporation heat exchanger and the preheating heat exchanger are both tube type heat exchangers with finned tubes, the fins are made of aluminum sheets, the spacing between the fins is 3mm to 6mm, and the height of the fins is 25mm to 45 mm.

8. The method for denitration by using the coke oven flue gas denitration and waste heat utilization combined device as claimed in any one of claims 1 to 7, is characterized by comprising the following steps:

(1) the temperature after desulfurization is 200 ℃ to 240 ℃, NO_XThe content is 600-1200mg/Nm³The flue gas enters the inlet flue through the flue gas inlet, the ammonia water steam enters the ammonia gas mixing component through the ammonia gas inlet pipeline and is sprayed out to be mixed with ammonia gas to obtain mixed gas, and NH is enabled to be generated₃The molar ratio of NO/is between 0.95 and 1.05,

(2) when the mixed gas passes through the gas burner, the gas burner heats the mixed gas, the heated mixed gas enters the catalyst layer through the flue gas flow equalizing component, and NH is generated under the catalytic action of the catalyst₃Reacting with NO;

(3) the NOx content in the denitrified smoke is less than 50mg/Nm³Sequentially contacting with an evaporation heat exchanger and a preheating heat exchanger, and after heat exchangeHas a temperature of 150 ~ 170 ℃ and is discharged through a clean flue gas outlet.

9. The method as claimed in claim 8, wherein the ammonia water vapor is obtained by vaporizing an ammonia water solution with a concentration of 10-20wt%, and the ammonia water vapor has a temperature of 140 ℃ and a volume flow of 900-1350m³Hr, flue gas flow rate of 54 ten thousand m³The speed of the jet pipe is more than or equal to 80 m/s.

Technical Field

The invention belongs to the field of coke oven flue gas denitration, and particularly relates to a coke oven flue gas denitration and waste heat utilization combined device and a denitration method by using the same.

Background

For flue gas denitration, a reduction method using ammonia as a raw material is mature and reliable, and the reaction principle is as follows: NO +0.25O₂+NH₃＝N₂+1.5H₂O, ammonia reduces NOx to nitrogen and water, eliminating pollution. 1mol of NO consumes 1mol of ammonia, converted to 1 ton of NO₂0.37 ton of ammonia was consumed. The project is designed according to the maximum value, and the consumed ammonia per hour is 130 kg. The methods are classified into non-catalytic selective reduction (SNCR) methods without a catalyst and Selective Catalytic Reduction (SCR) methods with a catalyst. The SNCR method requires that the reaction temperature is 850 ℃ and 950 ℃ and the denitration efficiency is 50-70%. It is clear that coke oven flue gas is not suitable for SNCR.

The coke oven flue gas has the following characteristics:

(1) the temperature is lower, the general temperature is between 200-2240 ℃, and the normal temperature is about 220 ℃. Although the temperature of the flue gas is also reduced to about 1300-1500 ℃, due to the particularity of the coke oven structure (adopting a heat storage heat exchange mode, and adopting a tubular heat exchange mode for a boiler), the catalyst layer can hardly be inserted in series in the coke oven, and the denitration can only be implemented by utilizing the temperature zone of the flue gas.

(2) The NOx content of the flue gas is higher and is 800-1200mg/Nm³In the meantime.

(3) The dust content is low, and is generally 30mg/Nm³About less than 100mg/Nm³。

Thus, conventional boiler catalysts are not well suited for denitration of coke oven flue gas.

The residual heat brought by the coke oven flue gas accounts for nearly one third of the residual heat utilization of the whole coking system. In order to save a smoke outlet induced draft fan and possible problems thereof in the past, smoke is directly discharged from an underground flue communicated chimney, and for a combustion chamber of a coke oven, the smoke directly forms creeping force to provide air for the coke oven.

In recent years, with the improvement of energy conservation, especially environmental protection standard, the utilization of the waste heat of the flue gas of the coke oven becomes an important direction. However, the existing waste heat utilization device is easy to have the problem of operation stability due to the particularity of the coke oven flue gas.

Disclosure of Invention

The invention aims to provide a coke oven flue gas denitration and waste heat utilization combined device and a denitration method by using the same.

Based on the purpose, the invention adopts the following technical scheme:

the utility model provides a coke oven flue gas denitration and waste heat utilization combined device, includes entry flue, denitration reactor and steam pocket, the entry flue is equipped with flue gas inlet, ammonia inlet pipe and three exhanst gas outlet pipe, every exhanst gas outlet pipe links to each other with the import that denitration reactor top corresponds, be equipped with clean exhanst gas outlet on the lower part casing of denitration reactor, be equipped with flue gas flow equalizing member, denitration catalyst, evaporation heat exchanger and preheating heat exchanger from last to down in proper order in the denitration reactor cavity of clean exhanst gas outlet top, the import and the export of evaporation heat exchanger link to each other through pipeline and steam pocket respectively, the import of preheating evaporator even has soft water pipeline, the export of preheating evaporator links to each other through hot water pipeline and steam pocket, the steam pocket is equipped with steam output tube.

Further, the entry flue is the S type, by last horizontal part, vertical portion of horizontal part and connection lower horizontal part constitutes, the left end import of lower horizontal part is the flue gas inlet, the right-hand member branch of going up the horizontal part is equipped with three exhanst gas outlet pipe ways, all be equipped with the gas burner on every exhanst gas outlet pipe way, gas burner and gas line intercommunication, the top of denitration reactor is equipped with three import, three exhanst gas outlet pipe ways link to each other with the three import at denitration reactor top respectively, be equipped with two division boards in the cavity of denitration reactor, the division board upwards extends to the top of denitration reactor cavity, downwardly extending to the bottom of denitration catalyst.

And further, an ammonia gas mixing component is arranged below the vertical part of the inlet flue and is connected with an ammonia gas inlet pipeline outside the inlet flue, the ammonia gas mixing component comprises an ammonia gas branch pipe, and a jet pipe is vertically arranged on the ammonia gas branch pipe.

Further, the denitration catalyst is provided with three layers at intervals from top to bottom, the filling height of each layer is 1.0-1.8 m, and the distance between adjacent layers is 1.0-1.6 m.

Further, the flue gas flow equalizing member is a pore plate, the thickness of the pore plate is 6-20 mm, the opening of the pore plate is a square hole, a round hole or a strip-shaped hole, and the flow area of the hole is one fourth to one third of the cross-sectional area of the denitration reactor.

Further, the catalyst is honeycomb-shapedThe catalyst is characterized in that honeycomb holes are round holes, square holes or hexagonal holes, the size of the honeycomb holes is 3-6 mm, and the honeycomb catalyst contains MoO₃V of₂O₅/TiO₂Catalyst and MoO₃In the mass of the catalyst is between 2.5 and 5 percent of the total mass of the catalyst, V₂O₅The mass of (A) is 1.5 to 3.0% of the total catalyst.

Furthermore, the evaporation heat exchanger and the preheating heat exchanger are both tube type heat exchangers with finned tubes, the fins are made of aluminum sheets, the distance between the fins is 3mm to 6mm, and the height of the fins is 25mm to 45 mm.

The method for denitration by using the coke oven flue gas denitration and waste heat utilization combined device comprises the following steps:

(1) the temperature after desulfurization is 200 ℃ to 240 ℃, NO_XThe content is 600-1200mg/Nm³The flue gas enters the inlet flue through the flue gas inlet, the ammonia water steam enters the ammonia gas mixing component through the ammonia gas inlet pipeline and is sprayed out to be mixed with ammonia gas to obtain mixed gas, and NH is enabled to be generated₃The molar ratio of NO/is between 0.95 and 1.05,

(2) when the mixed gas passes through the gas burner, the gas burner heats the mixed gas, the heated mixed gas enters the catalyst layer through the flue gas flow equalizing component, and NH is generated under the catalytic action of the catalyst₃Reacting with NO;

(3) the NOx content in the denitrified smoke is less than 50mg/Nm³Sequentially contacting with an evaporation heat exchanger and a preheating heat exchanger, wherein the temperature of flue gas after heat exchange is 150-170 ℃, and discharging the flue gas through a clean flue gas outlet.

Preferably, the ammonia water vapor is obtained by vaporizing an ammonia water solution with the concentration of 10-20wt%, the temperature of the ammonia water vapor is 140 ℃, and the volume flow is 900-³Hr, flue gas flow rate of 54 ten thousand m³The speed of the jet pipe is more than or equal to 80 m/s.

By using the device and the catalyst, the emission of NOx is reduced to 2500 tons every year, the quantity of recovered steam is 10 ten thousand tons every year, and the denitration efficiency is as follows: greater than 96%; outlet NOx: less than 50mg/Nm³The service cycle of the catalyst is more than two years, and good economy is obtainedAnd (4) benefit.

Drawings

FIG. 1 is a schematic structural diagram of a combined device for denitration and waste heat utilization of coke oven flue gas;

fig. 2 is a schematic view of the ammonia mixing component of fig. 1.

Detailed Description

The technical solutions of the present invention are further described in detail below with reference to the drawings and examples, but the present invention is not limited thereto.