CN212999345U

CN212999345U - Ammonia steam mixing and spraying device of SCR denitration system adopting urea hydrolysis method

Info

Publication number: CN212999345U
Application number: CN202020777897.XU
Authority: CN
Inventors: 朱庭旺; 郝哲晶; 朱浩庆; 高锋
Original assignee: Changchun No2 Co Generation Power Co ltd
Current assignee: Changchun No2 Co Generation Power Co ltd
Priority date: 2020-05-12
Filing date: 2020-05-12
Publication date: 2021-04-20
Anticipated expiration: 2030-05-12

Abstract

The utility model provides an ammonia of urea hydrolysis method SCR deNOx systems evaporates mixed injection apparatus, belongs to thermal power equipment and reforms transform technical field. The utility model aims at providing an use reheat steam to evaporate mixing injection apparatus as the medium of diluting the ammonia, the urea hydrolysis method SCR deNOx systems of pressure boost source. The utility model discloses install communicating side ammonia pipeline on the pipeline between the ammonia flowmeter of ammonia pipe-line system and the manual door behind the ammonia adjustment gate, the side ammonia pipeline is evaporated through suction chamber ammonia pipe and is mixed booster intercommunication, and the ammonia evaporates mixed booster and whirl pipeline pass through the pipeline intercommunication, and the whirl pipeline evaporates the pipeline through the side ammonia and communicates with flute tubular spray gun mechanism, and flute tubular spray gun mechanism arranges in the flue gas pipeline; and a pipeline between the manual door behind the ammonia gas adjusting door and the ammonia-air mixer is communicated with a steam spray pipe of the ammonia-steam mixing supercharger through a bypass pipeline. The utility model provides a local easy jam problem of deNOx systems, spout ammonia volume too big, export NOx inhomogeneous, ammonia escape rate high and denitration inefficiency scheduling problem.

Description

Ammonia steam mixing and spraying device of SCR denitration system adopting urea hydrolysis method

Technical Field

The utility model belongs to the technical field of thermal power equipment reforms transform.

Background

Selective Catalytic Reduction (SCR) denitration technology for flue gas of coal-fired boiler, which is the most mature flue gas denitration technology with the highest denitration efficiency at present. The selection and application technology of the reducing agent are key links of SCR engineering application. At present, liquid ammonia and urea are widely used as a plurality of reducing agents in China, but from the aspects of factors such as safety, field and operation, the urea hydrolysis process is selected in most power plants in China. The denitration by the urea hydrolysis method is characterized in that 50% of urea solution is pyrolyzed under the conditions of high temperature and high pressure to generate hydrolyzed ammonia containing 28.3% of ammonia, 36.7% of carbon dioxide and 35% of water vapor through chemical reaction, the hydrolyzed ammonia is sprayed into a flue through diluted hot air to enable the ammonia and NOx in flue gas to be fully mixed and react to generate nitrogen and water, and a catalyst enables the NOx in the flue gas to rapidly react with the ammonia at the temperature of 300-420 ℃, so that the aim of denitration is fulfilled. The ammonia gas and flue gas mixing device is a key part of the SCR denitration system, and due to the chemical characteristics of the ammonia gas, the hydrolyzed ammonia gas needs to be mixed and diluted with hot air of a boiler by an ammonia-air mixer (AAM) until the volume fraction is reduced to about 5 percent, enters an Ammonia Injection Grid (AIG) system, is mixed, diluted and pressurized, and then reacts with NOx in a flue. The prior ammonia-air mixing and grid ammonia spraying mode has at least the following disadvantages in the operation process:

firstly, the problems of corrosion and blockage of condensed crystal substances frequently occur to an ammonia spraying flow regulating valve, a flow meter and an ammonia spraying flute pipe:

the hydrolyzed ammonia gas has high humidity and strong corrosivity and contains biuret and other condensation compounds, and is very easy to condense into a crystal under the condition of temperature reduction (lower than 130 ℃ C.), because a flow regulating valve, a flowmeter and an ammonia spraying nozzle have throttling effects, the impurities generated by the condensate and pipeline corrosion are easy to accumulate and block at the position, the original design does not have an online dredging and purging device, the pipeline is blocked by the crystallization of the condensate, so that the flow of the hydrolyzed ammonia gas cannot meet the requirement of the environmental protection denitration efficiency, and the blockage seriously needs to start a bypass to operate or stop the furnace for treatment.

Secondly, the problem of blockage of ash accumulation slab knots in the ammonia air mixer, the mixing header and the ammonia spraying grid is solved:

in order to achieve the purpose that hydrolyzed ammonia gas can be uniformly mixed with NOx in flue gas, ammonia-air mixed gas with dilution air as a driving carrier needs a large amount of high-pressure-head hot dilution air, in the prior art, boiler hot primary air is extracted (by using a 50KW centrifugal fan) to serve as dilution air, air leakage rate exists due to the adoption of a rotary air preheater, dust in the flue gas can leak to the primary air side, the dust content of primary hot air is increased, the hydrolyzed ammonia gas and ash in the dilution air are easy to fuse to generate a hardening phenomenon, the hardened ash blocks an ammonia-air mixer, a mixing header and an ammonia injection grid, the high-pressure head of the ammonia-air mixed air is low, online treatment cannot be performed, and the ammonia input amount must be increased to meet the denitration efficiency in the early stage of blocking.

Thirdly, the ammonia-air mixing type injection system has problems in the structural design of equipment and the position selection of a temperature field:

the ammonia-air mixing type injection system has structural arrangement asymmetry in the form of an ammonia injection grid, the arrangement temperature field position selected by the ammonia injection grid is unreasonable and is close to a reactor catalyst, ammonia and NOx in flue gas cannot be fully mixed in a short distance after ammonia-air mixture is injected into a flue, and the ammonia and NOx in the flue gas on the upper portion of a top layer catalyst are not uniformly distributed and react insufficiently to influence denitration efficiency. In addition, the system blockage problem promotes the increase of the input ammonia amount, so that the problems of urea waste, high ammonia escape rate, low denitration efficiency and the like caused by the increase of the input ammonia amount are solved.

Disclosure of Invention

The utility model aims at providing an use reheat steam to evaporate mixing injection apparatus as the medium of diluting the ammonia, the urea hydrolysis method SCR deNOx systems of pressure boost source.

The utility model discloses install communicating side ammonia pipeline on the pipeline between the ammonia flowmeter of ammonia pipe-line system and the ammonia adjustment gate back hand-operated gate, the side ammonia pipeline is evaporated through suction chamber ammonia pipe and is mixed booster intercommunication, and the ammonia evaporates mixed booster passes through the pipeline with the whirl pipeline and communicates, and the whirl pipeline evaporates the pipeline through the side ammonia and communicates with flute tubular spray gun mechanism, has set gradually ammonia and evaporates hand-operated gate, flow orifice plate and mixer flow gate on the side ammonia pipeline, and flute tubular spray gun mechanism arranges in the flue gas pipeline; a pipeline between the manual door behind the ammonia gas adjusting door and the ammonia-air mixer is communicated with a steam spray pipe of the ammonia-steam mixing supercharger through a bypass pipeline;

the flute type spray gun mechanism comprises: the upper side surface of the side ammonia evaporation vertical pipe is communicated with a flute pipe spray gun, the wall of the flute pipe spray gun is provided with spray gun spray holes, and the flute pipe spray gun is arranged on one side of a smoke outlet of a smoke pipeline;

ammonia distillation mixing supercharger: the ammonia pipe of the suction chamber is communicated with the rear section of the ammonia steam mixing and pressurizing pipe, the front section of the ammonia steam mixing and pressurizing pipe is a diameter-reduced ammonia steam mixing and pressurizing pipe, a side branch pipeline is inserted into a steam spray pipe inside the ammonia steam mixing and pressurizing pipe, the diameter-reduced front section of the steam spray pipe is arranged in the diameter-reduced ammonia steam mixing and pressurizing pipe, and an ammonia steam mixed gas channel is arranged between the outer wall of the diameter-reduced front section and the inner wall of the diameter-reduced ammonia steam mixing and pressurizing pipe;

a spiral vortex sheet is arranged in the vortex pipeline;

the communication part of the side ammonia evaporation pipeline and the flute type spray gun mechanism is a three-way pipeline, and a separation sheet is fixedly arranged on the side wall of the three-way pipeline corresponding to the air inlet direction of the side ammonia evaporation pipeline.

The utility model discloses the other pipeline of branch divide into other A pipeline and other B pipeline, and other A pipeline and other B pipeline have other A side steam hand door and other B side steam hand door respectively, and other A pipeline and other B pipeline evaporate the flute pipe formula spray gun mechanism that mixes in booster, the respective flue gas pipeline of whirl pipeline intercommunication respectively through independent ammonia separately.

The utility model provides a local easy jam problem of deNOx systems, spout ammonia volume too big, export NOx inhomogeneous, ammonia escape rate high and denitration inefficiency scheduling problem.

Drawings

FIG. 1 is a perspective view of the present invention;

fig. 2 is a side cross-sectional view of the present invention;

FIG. 3 is a schematic view of the flute-type spray gun mechanism of the present invention;

FIG. 4 is a schematic structural view of the ammonia distillation mixing supercharger of the present invention;

FIG. 5 is a sectional view of the interior of the cyclone pipeline;

FIG. 6 is a cross-sectional view of the inside of the tee pipe of the present invention;

FIG. 7 is a structural connection diagram of ammonia distillation mixed injection device of A, B two sets of denitration systems.

Detailed Description

Ammonia pipe-line system 1 is the feeding system of current ammonia and steam, the utility model discloses an improvement front portion is just gone on the original structure basis of the feeding system of current ammonia and steam, the solid line is the ammonia supply pipe way in 6 anterior segment coupling parts on whirl pipeline in figure 1 and figure 2, the dotted line is the steam supply pipeline, and the steam supply divide into two parts, the pipeline of first part steam supply is inside along with the straight-through whirl pipeline 6 in 3 sides of side ammonia pipeline, the pipeline of second part steam supply is side branch pipeline 4, side branch pipeline 4 communicates with each other with the steam spray tube 53 of ammonia steam mixing booster 5. The utility model discloses install communicating side ammonia pipeline 3 on the pipeline between ammonia flowmeter 13 of ammonia pipe-line system 1 and the ammonia adjustment gate back hand-operated gate 12, side ammonia pipeline 3 is through suction chamber ammonia pipe 51 and ammonia evaporation mixing booster 5 intercommunication, ammonia evaporation mixing booster 5 and whirl pipeline 6 are through the pipeline intercommunication, whirl pipeline 6 is through side ammonia evaporation pipeline 8 and flute tubular spray gun mechanism 9 intercommunication, set gradually ammonia evaporation hand-operated gate 7, flow orifice plate 14 and mixer flow gate 15 on side ammonia evaporation pipeline 8, flute tubular spray gun mechanism 9 is arranged in flue gas pipeline 10, the ammonia that flute tubular spray gun mechanism 9 erupted mixes with the flue gas that passes through; the pipeline between the manual door 12 behind the ammonia gas adjusting door and the ammonia-air mixer is communicated with the steam nozzle 53 of the ammonia steam mixing supercharger 5 through the bypass pipeline 4.

Flute type spray gun mechanism 9: the upper side surface of the side ammonia evaporation vertical pipe 93 is communicated with a flute pipe spray gun 91, the wall of the flute pipe spray gun 91 is provided with a spray gun spray hole 92, and the flute pipe spray gun 91 is arranged on one side of the smoke outlet of the smoke pipeline 10; the ammonia vapor mixed gas from the side ammonia vapor pipeline 8 enters the side ammonia vapor vertical pipe 93 and is extruded out from a plurality of spray gun jet holes 92 to be mixed with the flue gas in the flue gas pipeline 10. The number of the flute spray guns 91 is determined according to the size of the interior of the flue gas pipeline 10, and the aim is that the steam-mixed gas sprayed from the spray gun spray holes 92 completely covers the space of the interior of the flue gas pipeline 10.

Ammonia distillation mixing supercharger 5: the ammonia pipe 51 of the suction chamber is communicated with the rear section of the ammonia steam mixing pressure pipe 52, the front section of the ammonia steam mixing pressure pipe 52 is a diameter-reducing ammonia steam mixing pressure pipe 55, the side branch pipe 4 is inserted into the steam nozzle 53 inside the ammonia steam mixing pressure pipe 52, the diameter-reducing front section 54 of the steam nozzle 53 is arranged in the diameter-reducing ammonia steam mixing pressure pipe 55, and an ammonia steam mixed gas channel 56 is arranged between the outer wall of the diameter-reducing front section 54 and the inner wall of the diameter-reducing ammonia steam mixing pressure pipe 55; the ammonia vapor mixing booster 5 is a device for mixing ammonia gas and steam and increasing the pressure, wherein the ammonia gas is increased in speed by reducing the diameter of the ammonia vapor mixing booster 55, and the steam is increased in speed by reducing the diameter of the front section 54, and is mixed and accelerated at the part of the ammonia vapor mixing booster 55.

A spiral vortex sheet 61 is arranged in the vortex pipeline 6; the spiral swirl plate 61 is of a spiral structure, and when ammonia vapor is mixed and the vapor from the first part of vapor supply line passes through the spiral structure simultaneously to generate a swirl flow pattern, the vapor is sent to the side ammonia vapor line 8.

The part of the side ammonia evaporation pipeline 8 communicated with the flute type spray gun mechanism 9 is a three-way pipeline 21, and a separation sheet 22 is fixedly arranged on the side wall of the three-way pipeline 21 corresponding to the air inlet direction of the side ammonia evaporation pipeline 8. The ammonia vapor mixture from the side ammonia vapor pipeline 8 is divided in advance by a partition plate 22 and then sent into a branch of a tubular spray gun mechanism 9. In order to improve the coverage rate of the spraying range of the flute-shaped spray gun mechanism 9, the flute-shaped spray gun mechanism 9 generally comprises at least two side ammonia evaporation pipes 93, and the side ammonia evaporation pipe 8 only comprises one pipe, so the three-way pipe 21 is adopted for conveniently and completely supplying gas to the at least two side ammonia evaporation pipes 93.

The utility model discloses other branch pipeline 4 divide into other A pipeline 17 and other B pipeline 18, and other A pipeline 17 and other B pipeline 18 have other A side steam hand door 20 and other B side steam hand door 19 respectively, and other A pipeline 17 and other B pipeline 18 evaporate the flute pipe type spray gun mechanism that mixes in booster, the respective flue gas pipeline of whirl pipeline intercommunication respectively through independent ammonia separately and construct. The part is a local structural change performed when the original ammonia pipeline system 1 and the original flue gas pipeline 10 are both two sets (respectively, the system is divided into a system a and a system B).

The utility model discloses an utilize reheat steam as the dilution of ammonia of hydrolysising, the pressure boost source, realize the ammonia pipeline companion heat and the inside abluent function of equipment simultaneously, evaporate the inside ammonia of hydrolysising of mixed injection apparatus at the ammonia and absorb the steam heat, the formation rate of ammonia has further been improved, the mixed gas pressure and the velocity of flow distribution that jet out through flute pipe formula spray gun are even, according to designing accurate and flue gas pass through catalyst high efficiency reaction at best temperature field intensive mixing, the consumption and the ammonia escape rate that reduce the reductant have been played, the effect of catalyst life-span and SCR denitration efficiency is improved.

The ammonia evaporation mixing and spraying device does not need to extract a large amount of hot primary air of the boiler, stops running the dilution fan to play the roles of saving energy and reducing consumption, and reduces the influence on the normal operation of the boiler. The original ammonia-air mixing type injection system can be reserved as emergency standby equipment, and the safety and the reliability of environmental protection facilities are improved.

The ammonia evaporation mixed injection device has the advantages of reasonable structure, simple arrangement, small engineering quantity, safety and high denitration efficiency, completely meets the safe operation of the ultralow emission standard of the boiler through one-year operation, and generates huge comprehensive benefits.

The ammonia introduced by the novel ammonia evaporation mixing injection device is from a urea hydrolyzer and is formed by welding a pipeline, a stop valve and an outlet of an ammonia supply flow regulating valve of a hydrolyzer system, the required ammonia consumption is calculated and determined by a hydrolysis control system according to the content of nitrogen oxides in flue gas during operation, and the input amount of the ammonia is controlled by an ammonia adjusting door. The ammonia vapor mixing and spraying device adopts 300 ℃ cold-stage reheated steam as a dilution and pressurization source of hydrolyzed ammonia gas. The reheat steam leading pipeline and the hydrolysis ammonia pipeline are wrapped in parallel for heat preservation, and the reheat steam leading pipeline and the hydrolysis ammonia pipeline are heated and accompanied by heat. The method is characterized in that reheat steam is introduced into the inlet pipe section of the ammonia hydrolysis regulating valve, equipment such as ammonia hydrolysis pipelines and valves is periodically purged and cleaned by controlling a reheat steam stop valve switch, and a stop valve is installed at the tail end of the reheat steam introduction pipeline and welded with an inlet nozzle pipe of an ammonia steam mixing supercharger. The ammonia evaporation mixed supercharger (see figure 4) is composed of four parts, namely a steam nozzle, a tubular suction chamber, a suction chamber ammonia pipe and a mixed diffuser pipe, and is used for realizing functions by utilizing a jet flow negative pressure principle, high-temperature and high-pressure steam is sprayed out from the nozzle at a high speed, when the high-speed flowing steam passes through the tubular suction chamber, vacuum can be formed in the suction chamber, hydrolyzed ammonia gas is sucked into an ammonia pipe of the suction chamber and is introduced into a diffuser pipe section to form mixed gas, and the high-pressure ammonia evaporation mixed gas sprayed out through the mixed diffuser pipe enters an ammonia evaporation mixed gas conveying pipe. The inside assembly welding of gas mixture conveyer pipe has the spinning disk (see fig. 5), and its effect utilizes the high-pressure draught to make the ammonia evaporate the mixture more intensely through the principle that spiral spinning disk can produce high-speed revolving force, and the steam that density is big simultaneously can play the cleaning action to the equipment inner wall. The isosceles tee pipe fitting is internally provided with a welding separation sheet (see figure 6), and the function of the isosceles tee pipe fitting is to eliminate pressure disturbance between the left outlet and the right outlet of the tee pipe fitting by using the separation sheet, so that the ammonia vapor mixture is uniformly distributed. The mixed gas conveying pipe is provided with a flow orifice plate, the function of the mixed gas conveying pipe is to measure the flow of each pipeline by utilizing a differential pressure principle, the pressure and the flow velocity of the ammonia vapor mixed gas ejected by each flute pipe type spray gun are ensured to be uniform by accurately controlling each mixed gas flow regulating valve, the hydrolyzed ammonia gas in the ammonia vapor mixed injection device absorbs the heat of the steam, and the generation rate of the ammonia gas is further improved. The equal-spacing, staggered, vertical and downstream design of the flute-type spray guns (see figure 3) is arranged in the measured optimal flue temperature field, 38 phi 2mm spray holes can be uniformly arranged in each square meter of the cross section of the flue, the ammonia steam mixed gas has strong capability of penetrating through flue gas, the flue temperature field newly provided with an ammonia gas injection point is far away from the catalyst, the ammonia and NOx in the flue gas entering the upper part of the top catalyst are uniformly distributed and fully reacted in a mixed mode, the ammonia injection amount and the ammonia escape rate are effectively reduced, and the service life of the catalyst is prolonged and the SCR denitration efficiency is improved.

The utility model discloses mixed injection apparatus system is evaporated to ammonia compares with former ammonia system, effectively solves AIG and spouts the easy jam of ammonia pipeline, the easy crystallization of ammonia pipeline, the shutdown dilution fan and save the power consumption scheduling problem. The novel ammonia evaporation mixed injection device system has the characteristics of reasonable structure, simple arrangement, small engineering quantity and the like. The method realizes three factors of high-efficiency denitration, an optimal reaction temperature field, good mixing and sufficient reaction time, completely meets the safe operation of the ultralow emission standard of the boiler through one-year operation, and generates huge comprehensive benefits.

Claims

1. The utility model provides an ammonia of urea hydrolysis method SCR deNOx systems evaporates mixed injection apparatus which characterized in that: a communicated side ammonia pipeline (3) is arranged on a pipeline between an ammonia flowmeter (13) of an ammonia pipeline system (1) and an ammonia adjusting gate rear manual gate (12), the side ammonia pipeline (3) is communicated with an ammonia evaporation mixing supercharger (5) through an ammonia pipe (51) of a suction chamber, the ammonia evaporation mixing supercharger (5) is communicated with a rotational flow pipeline (6) through a pipeline, the rotational flow pipeline (6) is communicated with a flute tube type spray gun mechanism (9) through a side ammonia evaporation pipeline (8), an ammonia evaporation manual gate (7), a flow pore plate (14) and a mixer flow gate (15) are sequentially arranged on the side ammonia evaporation pipeline (8), and the flute tube type spray gun mechanism (9) is arranged in a smoke pipeline (10); a pipeline between the rear manual door (12) of the ammonia gas adjusting door and the ammonia-air mixer is communicated with a steam spray pipe (53) of the ammonia-steam mixing supercharger (5) through a bypass pipeline (4);

a flute-type lance mechanism (9): the upper side surface of the side ammonia evaporation vertical pipe (93) is communicated with a flute pipe spray gun (91), the wall of the flute pipe spray gun (91) is provided with a spray gun spray hole (92), and the flute pipe spray gun (91) is arranged on one side of a smoke outlet of the smoke pipeline (10);

ammonia vapor mixing booster (5): an ammonia pipe (51) of the suction chamber is communicated with the rear section of the ammonia evaporation mixing booster pipe (52), the front section of the ammonia evaporation mixing booster pipe (52) is a diameter-reduced ammonia evaporation mixing booster pipe (55), a side branch pipeline (4) is inserted into a steam spray pipe (53) in the ammonia evaporation mixing booster pipe (52), the diameter-reduced front section (54) of the steam spray pipe (53) is arranged in the diameter-reduced ammonia evaporation mixing booster pipe (55), and an ammonia evaporation mixed gas channel (56) is arranged between the outer wall of the diameter-reduced front section (54) and the inner wall of the diameter-reduced ammonia evaporation mixing booster pipe (55);

a spiral swirl plate (61) is arranged in the swirl pipeline (6);

the communication part of the side ammonia evaporation pipeline (8) and the flute type spray gun mechanism (9) is a three-way pipeline (21), and a separation sheet (22) is fixedly arranged on the side wall of the three-way pipeline (21) corresponding to the air inlet direction of the side ammonia evaporation pipeline (8).

2. The ammonia vapor mixing and injecting device of the urea hydrolysis method SCR denitration system according to claim 1, wherein: the branch pipeline (4) is divided into a branch A pipeline (17) and a branch B pipeline (18), the branch A pipeline (17) and the branch B pipeline (18) are respectively provided with a branch A side steam manual door (20) and a branch B side steam manual door (19), and the branch A pipeline (17) and the branch B pipeline (18) are respectively communicated with flute type spray gun mechanisms in the flue gas pipelines respectively through an ammonia steam mixing supercharger and a cyclone pipeline which are independent of each other.