CN206222297U - A kind of multiplex control system of grate furnace nitrogen oxide emission - Google Patents

Abstract

The utility model belongs to the technical field of boiler energy-saving and environmental protection, and disclose a kind of multiplex control system of grate furnace nitrogen oxide emission, the system includes grate furnace body, carries staged combustion device, SNCR denitration device, Multifunctional smoke on-line computing model and the PLC control system of flue gas recirculation；Staged combustion device is evenly distributed on the wall of burner hearth both sides, its inlet end is provided centrally with blast pipe, the blast pipe other end sets adiabatic steady flame bluff body, inlet end wall is additionally provided with Secondary Air cyclone, one end away from inlet end is additionally provided with stable burning cavity, and the mixture of appropriate coal dust or combustion gas, fresh air and circulating flue gas is sprayed into grate furnace by the staged combustion device.The multiplex control system of the utility model is remarkably improved fuel oxidation reaction speed and fire box temperature uniformity, full combustion of fuel and low nitrogen burning can be realized, coefficient of excess air is reduced, the dual lifting of denitration efficiency and the thermal efficiency is realized, the purpose of energy-saving and emission-reduction is reached.

Description

A kind of multiplex control system of grate furnace nitrogen oxide emission

Technical field

The utility model is related to the technical field of boiler energy-saving and environmental protection, more particularly, to a kind of grate furnace nitrogen oxidation The multiplex control system of thing discharge capacity, it can realize full combustion of fuel and low nitrogen burning, realize denitration efficiency and the thermal efficiency Dual lifting.

Background technology

Coal-burning boiler is divided into grate furnace and the class of room burner two, and wherein grate furnace capacity is relatively small, but because of simple structure, behaviour Make convenient and not high to stoker's personnel qualifications and be widely used, its accounting is up to 60~70% according to statistics, its application time And many industry fields such as building materials, chemical industry, printing and dyeing, heat treatment, pharmacy.Grate furnace dispatch from the factory design when more focus on efficiency of combustion, Based on energy-conservation, to NOx (nitrogen oxides) and SO₂Discharge concern is less.In recent years, as boiler desulfurization denitration transformation is gradually deep Enter, large number of grate furnace pollutant emission attracts attention increasingly.By current standard, the NOx emission limit value of key area is 200mg/Nm³, existing grate furnace discharges below standard, it would be highly desirable to carry out NOx emission control transformation.

At present, grate furnace NOx emission control technology is mainly with flue gas recirculation and SNCR (SNCR) Main or its United Technologies.

Flue gas recirculation principle is to add into combustion air 20~30% flue gas recirculation, by reducing combustion air The method reduction combustion zone temperature of oxygen content, so as to suppress the generation of NOx, the know-why is simple, and investment is little, denitration efficiency About 10~30%, but it is limited to grate furnace combustion system, its combustion intensity is low, and burning velocity is not also high, and flue gas recirculating technique exists Exist in application process must limitation, specific manifestation is as follows：When 1. selecting flue gas recirculating technique, there is ash content carbon The problems such as raising and further reduce fire box temperature, causes the grate furnace thermal efficiency to decline.If 2. from flue gas recirculation and SNCR United Technologies, also can because fire box temperature is relatively low and reaction temperature windows narrow reduce the denitration efficiency of SNCR.

SNCR technologies are SNCR technology (selective non-catalytic reduction), are made Reducing agent is urea or ammoniacal liquor, is sprayed into stove, can be with NO and NO in 800~1000 DEG C of temperature range₂Produce Reduction reaction, generates nitrogen and water.Because grate furnace furnace cavity finite sum furnace temperature is relatively low, more from the ammoniacal liquor that reaction temperature is relatively low It is reducing agent.But in grate furnace application SNCR technologies, frequently encounter because fire box temperature skewness, space are limited and temperature Relatively low the problems such as and cause effectively spray ammonia point to find difficulty, reduction reaction deficiency of time, the escaping of ammonia rate and rise, and then influence denitration Efficiency, ammoniacal liquor consumption increases, and the escaping of ammonia can also produce serious atmosphere polluting problem.

Based on above technological deficiency, this area is needed badly and further improvement is made to existing grate furnace structure and is designed, Full combustion of fuel and low nitrogen burning are achieved, fuel oxidation reaction speed and fire box temperature uniformity is significantly improved, realized The dual lifting of denitration efficiency and the thermal efficiency.

Utility model content

For the disadvantages described above or Improvement requirement of prior art, the utility model provides a kind of grate furnace discharged nitrous oxides The multiplex control system of amount, is improved and is designed by the structure to grate furnace, using layer combustion+multiple spot levigation burning+ SNCR combination techniques, using staged combustion device, by the mixture of appropriate coal dust or combustion gas, fresh air and circulating flue gas with many Point fractional combustion mode is sprayed into grate furnace, and horizontal and vertical hybrid fuel air classification is formed above Ceng Ran areas, and in combustion Cinder area arrangement SNCR ammonia water spray gun carries out reduction reaction.The utility model can be used alone grading combustion technology or and SNCR denitration Technology is combined, and is remarkably improved fuel oxidation reaction speed and fire box temperature uniformity, realizes full combustion of fuel and low nitrogen Burning, reduces coefficient of excess air, realizes the dual lifting of denitration efficiency and the thermal efficiency.

To achieve these goals, a kind of compound control of grate furnace nitrogen oxide emission is provided according to the utility model System processed, it is characterised in that staged combustion device and/or SNCR denitration dress that it includes grate furnace body, carries flue gas recirculation Put, Multifunctional smoke on-line computing model and PLC control system；

The staged combustion device is arranged on the top of grate furnace body fire grate, and the SNCR denitration device is arranged on described The top of staged combustion device, the Multifunctional smoke on-line computing model is installed at the flue outlet of grate furnace afterbody, described PLC control system is connected with Multifunctional smoke on-line computing model；

Wherein, multiple staged combustion devices are evenly distributed on the wall of burner hearth both sides, and the staged combustion device enters Gas end is provided centrally with blast pipe, and for introducing center First air, the other end of blast pipe is provided with adiabatic steady flame bluff body, should Adiabatic steady flame bluff body is located at the center of the staged combustion device, and wall is close to also in the inlet end of the staged combustion device Secondary Air cyclone is provided with, for introducing Secondary Air, outer First air, institute can be introduced between blast pipe and Secondary Air cyclone One end that staged combustion device is stated away from inlet end is truncated into stable burning cavity beyond the one of adiabatic steady flame bluff body.

It is further preferred that the First air carries fuel, conveyed by fan mill；The Secondary Air is combustion air, by Secondary Air blower fan is conveyed, and above-mentioned First air is the mixture of fresh air, circulating flue gas and fuel with Secondary Air.

Preferably, the fuel is coal dust, coke-stove gas or gas, the content of fuel in the First air and Secondary Air It is 5~20%.Powdered or gaseous state shape the form of fuel can be greatly enhanced efficiency of combustion, reduce and waste and reduce dirty Dye, moreover it is possible to reduce the fuel consumption cost of grate furnace.

Preferably, SNCR denitration device includes reductant solution storage tank, densimeter, blender (3-3), solution pump, metering Distribute module, compressed air reservoir, solution spray gun and SNCR system control modules, the solution spray gun are arranged on the combustion of grate furnace Cinder area injection reductant solution carries out reduction reaction.

Preferably, the reductant solution is ammoniacal liquor.

Preferably, the multiplex control system also includes air blower and air-introduced machine, and the air blower and air-introduced machine are pacified respectively Air side-entrance and flue gas side outlet loaded on grate furnace air preheater.By air blower and the frequency of air-introduced machine during normal work Rate jointly controls realizes that boiler furnace negative pressure is adjusted, and controls oxygen content and gas residence time, it is ensured that fuel is abundant in stove Burning.

Preferably, the PLC control system embeds grate furnace fractional combustion control system and based on NOx feedback controls SNCR systems.

Based on load variations and temperature controlled fractional combustion control strategy：

Grate furnace is used for on-site production steam supply, and load fluctuation is to play to greatest extent based on multi-point injection frequently Staged combustion device is acted on, and using load variations and temperature controlled fractional combustion control strategy is based in the utility model, is had Body implementation method is as follows：

1) by in-site measurement, the thermo parameters method in grate furnace inner height direction under different load is obtained, and sets up layer combustion Furnace temperature field data storehouse；

2) by numbered analog simulation, binder course furnace temperature field data storehouse model obtains a kind of preferably grate furnace point Level burner distribution scheme；

3) in process of production, the load variations according to grate furnace and combination temperature field data storehouse, system judge to need to throw Enter which layer or several layers of staged combustion devices, overall lifting fire box temperature and its uniformity are maintained at SNCR reaction temperatures all the time It is interval interior in a preferably temperature window, and fire box temperature lifting can improve the combustion position in coal seam on fire grate, have energy-conservation concurrently And environmental benefit.

Specifically, performed by boiler staged burning device control system, automatically adjust coal-supplying amount/powder-feeding amount, by air blower Frequency and coal-supplying amount/powder-feeding amount chain control；Combustion chamber draft regulation simultaneously is adjusted by air-introduced machine control combustion chamber draft, is thus extended Burning time of the fuel in burner hearth, it is ensured that full combustion of fuel, the purpose of energy-conservation is reached, while keeping boiler internal loading Stabilization, also improves the security of boiler.

In general, by the contemplated above technical scheme of the utility model compared with prior art, possess following excellent Point and beneficial effect：

(1) multiplex control system of the grate furnace nitrogen oxide emission that the utility model is provided, it uses fractional combustion With SNCR combination techniques, the former has energy-conservation and low nitrogen effect, and the latter is nitrogen oxides reduction technique.The two is used in combination, energy Fuel oxidation reaction speed and fire box temperature uniformity are enough significantly improved, coefficient of excess air is reduced, denitration efficiency and heat is realized The dual lifting of efficiency.And different user feature is directed to, the two can be applied alone or in combination, can fully meet different situations The need for lower.

(2) in the utility model provide the staged combustion device for carrying flue gas recirculation based on multi-point injection fractional combustion Can increase reactivity, reduce combustion zone oxygen content and effectively eliminate area of localized hyperthermia with flue gas recirculation powder delivery method, so as to have There is preferable low nitrogen burning effect.Fire box temperature and increase reaction interval can be also integrally lifted, makes fuel combustion more abundant, helped In raising SNCR denitration efficiency, and fire box temperature raises the combustion position that can improve coal seam on fire grate in turn, energy-conservation and ring Protect effect obvious.

(3) burner of the staged combustion device of the application uses diffusion combustion mode, increases burning adjustable range；It sets Adiabatic steady flame bluff body and Secondary Air cyclone are put, high temperature low speed recirculating zone is formed in combustion chamber；Preposition stable burning cavity is also set up, is protected Card fuel and air-stable and fully burning；Designed using Secondary Air flow velocity high and low First air flow velocity, so using flow velocity Difference improves mixing velocity, it is ensured that combustion completion；Due to the presence of center First air air-flow, its high temperature exported in steady flame bluff body Caught fire first in the recirculating zone of low speed, form flame on duty, main flow is lighted afterwards, burner combustion stabilization is greatly improved Property.The staged combustion device for carrying flue gas recirculation is based on air classification and the combustion method of flue gas recirculation is low nitrogen burning Effective means, advantageously reduce the high-temperature region temperature and oxygen concentration of burner outlet, and then the life of nitrogen oxide is greatly reduced Cheng Liang.

(4) the application is additionally provided with SNCR devices, and setting lance ejection reductant solution in the burnt zone of grate furnace is carried out Reduction reaction, denitration process are carried out by tail gas, can effectively reduce nitrogen oxide emission, meet the demand of environmental protection.

(5) multiplex control system of the application only need to be slightly modified i.e. available in existing equipment, it is not necessary to overall More exchange device, saves expense, is adapted to be promoted on a large scale.

Brief description of the drawings

Fig. 1 is the multiplex control system overall structure diagram of grate furnace nitrogen oxide emission of the present utility model.

Fig. 2 is the process chart of the staged combustion device for carrying flue gas recirculation of the present utility model.

Fig. 3 is the staged combustion device schematic diagram for carrying flue gas recirculation of the present utility model.

Fig. 4 is SNCR denitration device control principle drawing of the present utility model.

Fig. 5 is PLC system control flow chart of the present utility model.

In all of the figs, identical reference be used for represent identical element or structure, wherein：

1 grate furnace body, 2 staged combustion devices, 3 SNCR denitration devices, 4 Multifunctional smoke on-line computing models, 5 Air blower, 6 air-introduced machines, 7 PLC control systems, 3-1 reducing agent liquid storage tanks, 3-2 densimeters, 3-3 blenders, 3-4 solution Pump, 3-5 metering distribute modules, 3-6 compressed air reservoirs, 3-7 solution spray guns, 3-8 SNCR system control modules.

Specific embodiment

In order that the purpose of this utility model, technical scheme and advantage become more apparent, below in conjunction with accompanying drawing and implementation Example, is further elaborated to the utility model.It should be appreciated that specific embodiment described herein is only used to explain this Utility model, is not used to limit the utility model.Additionally, involved in the utility model disclosed below each implementation method As long as and to technical characteristic do not constitute each other conflict can just be mutually combined.

The utility model is described in further detail with reference to the accompanying drawings and detailed description.

The overall structure of the multiplex control system of the grate furnace nitrogen oxide emission that Fig. 1 is provided for the utility model is illustrated Figure.As shown in figure 1, the multiplex control system of the grate furnace nitrogen oxide emission includes grate furnace body 1, carries flue gas recirculation Staged combustion device 2 and/or SNCR denitration device 3, Multifunctional smoke on-line computing model 4 and PLC control system 7；

The staged combustion device 2 is arranged on the top of the fire grate of grate furnace body 1, and SNCR denitration device 3 is arranged on classification The top of burner 2, Multifunctional smoke on-line computing model 4 is installed at the flue outlet of grate furnace afterbody, PLC control system 7 are connected with Multifunctional smoke on-line computing model 4；

Wherein, multiple staged combustion devices 2 are evenly distributed on the wall of burner hearth both sides, the air inlet of staged combustion device 2 That holds is provided centrally with blast pipe, and for introducing center First air, the other end of blast pipe is provided with adiabatic steady flame bluff body, and this is exhausted Hot steady flame bluff body is located at the center of the staged combustion device 2, and wall is close to also in the inlet end of the staged combustion device 2 Secondary Air cyclone is provided with, for introducing Secondary Air, outer First air can be introduced between blast pipe and Secondary Air cyclone, point Level burner 2 is truncated into stable burning cavity away from one end of inlet end beyond the one of adiabatic steady flame bluff body.

In a specific embodiment of the present utility model, First air carries fuel, is conveyed by fan mill；Secondary Air is to help Combustion air, is conveyed by Secondary Air blower fan, and above-mentioned First air is the mixing of fresh air, circulating flue gas and fuel with Secondary Air Thing.

In another specific embodiment of the present utility model, fuel is coal dust, coke-stove gas or gas, in First air and The content of fuel is 5~20% in Secondary Air.

In another specific embodiment of the present utility model, SNCR denitration device 3 include reductant solution storage tank 3-1, Densimeter 3-2, blender 3-3, solution pump 3-4, metering distribute module 3-5, compressed air reservoir 3-6, solution spray gun 3-7 and SNCR system control modules 3-8, the burnt zone injection reductant solution that the solution spray gun 3-7 is arranged on grate furnace is reduced Reaction.

SNCR denitration device possesses ammoniacal liquor flow and concentration regulatory function, and boiler NOx control system feeds back according to measuring point NOx emission value, automatically adjusts ammonia spirit straying quatity, it is ensured that grate furnace NOx emission is controlled below setting value all the time, Neng Goushi When monitoring NOx discharge capacity and be adjusted at once so that reduce burning in generate NOx amount, reach the purpose of energy-saving and emission-reduction.

In another specific embodiment of the present utility model, reductant solution is ammoniacal liquor.

In another specific embodiment of the present utility model, multiplex control system also includes air blower 5 and air-introduced machine 6, The air blower 5 and air-introduced machine 6 are respectively arranged in air side-entrance and the flue gas side outlet of grate furnace air preheater.

In another specific embodiment of the present utility model, PLC control system 7 embeds grate furnace fractional combustion control system System and the SNCR systems based on NOx feedback controls.

Referring to Fig. 2 and Fig. 3, the staged combustion device fuel for carrying flue gas recirculation is coal dust or combustion gas, is different from often The Boiler Mixed Burning means of rule, the utility model uses multi-point injection and staged-combustion method, in the correct position of burner hearth both walls Multiple spot sprays into hearth combustion, and its burner is based on recirculating zone grading bamboo principle particular design, with preferable steady fuel efficiency really.

As shown in figure 3, the burner of the staged combustion device uses diffusion combustion mode, burning adjustable range is increased； It sets adiabatic steady flame bluff body and Secondary Air cyclone, and high temperature low speed recirculating zone is formed in combustion chamber；Also set up preposition steady combustion Chamber, it is ensured that fuel and air-stable and fully burning；Designed using Secondary Air flow velocity high and low First air flow velocity, it is so available Current difference improves mixing velocity, it is ensured that combustion completion；Due to the presence of center First air air-flow, it is exported in steady flame bluff body Caught fire first in the recirculating zone of high temperature low speed, form flame on duty, main flow is lighted afterwards, burner combustion is greatly improved steady It is qualitative.The staged combustion device for carrying flue gas recirculation is based on air classification and the combustion method of flue gas recirculation is low nitrogen combustion The effective means of burning, advantageously reduces the high-temperature region temperature and oxygen concentration of burner outlet, and then nitrogen oxide is greatly reduced Growing amount.

As shown in figs. 1 and 4, it is of the present utility model as follows based on the boiler fractional combustion control system course of work：In boiler During work, Load Regulation with traveling-grate stoker layer combustion burning based on, and by combustion gas or 5~20% coals in coal dust form by fractional combustion Device sends into burner hearth, and constant fire grate rotating speed adjusts boiler load by adjusting combustion gas or coal dust straying quatity.Meanwhile, system according to Positioned at CO and O that the Multifunctional smoke on-line computing model 4 of boiler economizer outlet will be measured in real time₂Etc. data transfer to boiler Fractional combustion control system, control system is according to discharge CO concentration in flue gas Vco and setting value V₀With setting deviation δ₀Ratio, if Measured value Vco ＜ V₀-δ₀, then it is more than needed according to system oxygen amount is shown, blower frequency is automatically turned down after system operations.If Vco ＞ V₀-δ₀, then according to system anoxic is shown, blower frequency is tuned up automatically after system operations.During control and regulation, all the time will CO concentration maintains micro state, makes natural fuel close to stoichiometric, and Oxygen Amount in Flue Gas is in 5%~10% level.System is being held Air-introduced machine hearth vacuum control is synchronously performed in row combustion control processes.

Referring to Fig. 4, there is the SNCR denitration device 3 regulation of reductant solution concentration and flue gas NOx to control two big functions, Can be made to measure according to boiler actual conditions, remain that SNCR is operated in suitable temperature window, keep denitration effect higher Rate.SNCR denitration device 3 operationally possesses concentration real-time regulation and flow real-time regulation, and system supervises Multifunctional smoke online Survey instrument 4 and detect subsystem --- SNCR system control modules, system that the NOx emission value for obtaining is fed back in PLC control system 7 Determine whether beyond sets requirement value range, and reductant solution penetrating is automatically adjusted according to result of determination and system control strategy Amount, so as to NOx emission is controlled below limit value.Work as NH₃When making reducing agent, SNCR reduction NOx reaction equations are as follows：

4NH₃+4NO+O₂→4N₂+6H₂O

4NH₃+2NO₂+O₂→3N₂+6H₂O

As it will be easily appreciated by one skilled in the art that preferred embodiment of the present utility model is the foregoing is only, not It is used to limit the utility model, all any modifications made within spirit of the present utility model and principle, equivalent and changes Enter, should be included within protection domain of the present utility model.

Claims (4)

1. a kind of multiplex control system of grate furnace nitrogen oxide emission, it is characterised in that it include grate furnace body (1), Carry the staged combustion device (2) and/or SNCR denitration device (3) of flue gas recirculation, Multifunctional smoke on-line computing model (4) and PLC control system (7)；

The staged combustion device (2) is arranged on the top of grate furnace body (1) fire grate, the SNCR denitration device (3) The top of the staged combustion device (2) is arranged on, the Multifunctional smoke on-line computing model (4) is installed on grate furnace afterbody At flue outlet, the PLC control system (7) is connected with Multifunctional smoke on-line computing model (4)；

Wherein, multiple staged combustion devices (2) are evenly distributed on the wall of burner hearth both sides, the staged combustion device (2) Inlet end is provided centrally with blast pipe, and the other end of blast pipe is provided with adiabatic steady flame bluff body, surely flame bluff body is located at for thermal insulation The center of the staged combustion device (2), the inlet end of the staged combustion device (2) be close to wall be additionally provided with it is secondary Wind cyclone, the staged combustion device (2) is truncated into steady combustion away from one end of inlet end beyond the one of the adiabatic steady flame bluff body Chamber.

2. the multiplex control system of grate furnace nitrogen oxide emission as claimed in claim 1, it is characterised in that the SNCR Denitrification apparatus (3) include reductant solution storage tank (3-1), densimeter (3-2), blender (3-3), solution pump (3-4), metering point With module (3-5), compressed air reservoir (3-6), solution spray gun (3-7) and SNCR system control modules (3-8), the solution spray Rifle (3-7) is arranged on the burnt zone of grate furnace.

3. the multiplex control system of grate furnace nitrogen oxide emission as claimed in claim 2, it is characterised in that described compound Control system also includes air blower (5) and air-introduced machine (6), and the air blower (5) is installed on the air of grate furnace air preheater Side-entrance, the air-introduced machine (6) is installed on the flue gas side outlet of grate furnace air preheater.

4. the multiplex control system of grate furnace nitrogen oxide emission as claimed in claim 3, it is characterised in that the PLC Control system (7) embeds grate furnace fractional combustion control system and the SNCR systems based on NOx feedback controls.