阅读说明：本技术 一种硫酸氢铵控制冷凝系统及方法 (Ammonium bisulfate condensation control system and method ) 是由 张知翔 徐党旗 赵锋 薛宁 姬海民 魏铜生 张广才 于 2021-09-17 设计创作，主要内容包括：本发明公开了一种硫酸氢铵控制冷凝系统及方法,空气预热器及烟气冷却器沿烟气流动方向依次设置于锅炉尾部烟道内；烟气冷却器的入水口与增压泵的出水口相连通,增压泵的入水口分别与N号低压加热器的入水口及N-1号低压加热器的出水口相连通,N-1号低压加热器的入水口与N号低压加热器的出水口相连通,N-2号低压加热器的入水口与N-1号低压加热器的出水口相连通,烟气冷却器的出水口与N-2号低压加热器的出水口相连通；暖风器的出风口与空气预热器的入风口相连通；锅炉尾部烟道内设置有若干吹灰器,各吹灰器均正对所述烟气冷却器,该系统方法能够降低空气预热器阻力及排烟温度,降低机组的供电煤耗。(The invention discloses a system and a method for controlling condensation of ammonium bisulfate, wherein an air preheater and a flue gas cooler are sequentially arranged in a flue at the tail part of a boiler along the flow direction of flue gas; the water inlet of the flue gas cooler is communicated with the water outlet of the booster pump, the water inlet of the booster pump is respectively communicated with the water inlet of the No. N low-pressure heater and the water outlet of the No. N-1 low-pressure heater, the water inlet of the No. N-1 low-pressure heater is communicated with the water outlet of the No. N-1 low-pressure heater, the water inlet of the No. N-2 low-pressure heater is communicated with the water outlet of the No. N-1 low-pressure heater, and the water outlet of the flue gas cooler is communicated with the water outlet of the No. N-2 low-pressure heater; the air outlet of the air heater is communicated with the air inlet of the air preheater; the system method can reduce the resistance and the smoke exhaust temperature of the air preheater and reduce the power supply coal consumption of the unit.)

1. An ammonium bisulfate condensation control system is characterized by comprising a flue gas cooler (2), a fan heater (7), an air preheater (1), a flue gas cooler (2), an N-number low-pressure heater (10), an N-1-number low-pressure heater (9) and an N-2-number low-pressure heater (8), wherein the air preheater (1) and the flue gas cooler (2) are sequentially arranged in a flue at the tail part of a boiler along the flow direction of flue gas;

the water inlet of the flue gas cooler (2) is communicated with the water outlet of a booster pump (11), the water inlet of the booster pump (11) is respectively communicated with the water inlet of a No. N low-pressure heater (10) and the water outlet of a No. N-1 low-pressure heater (9), the water inlet of the No. N-1 low-pressure heater (9) is communicated with the water outlet of the No. N low-pressure heater (10), the water inlet of a No. N-2 low-pressure heater (8) is communicated with the water outlet of the No. N-1 low-pressure heater (9), and the water outlet of the flue gas cooler (2) is communicated with the water outlet of the No. N-2 low-pressure heater (8);

the air outlet of the air heater (7) is communicated with the air inlet of the air preheater (1);

a plurality of soot blowers are arranged in the flue at the tail part of the boiler, and each soot blower is just opposite to the flue gas cooler (2).

2. The ammonium bisulfate condensation control system of claim 1, further comprising a flue gas treatment system, wherein the flue gas treatment system comprises an electric dust collector (3), an induced draft fan (4), a desulfurizing tower (5) and a chimney (6), and an outlet of the tail flue of the boiler is communicated with the chimney (6) through the electric dust collector (3), the induced draft fan (4) and the desulfurizing tower (5) in sequence.

3. Ammonium bisulfate control condensation system according to claim 1, wherein the flue gas cooler (2) is divided into a high temperature section (12) and a low temperature section (13), wherein soot blowers are arranged at the inlet and outlet of the high temperature section (12) and the inlet and outlet of the low temperature section (13).

4. The ammonium bisulfate control condensation system of claim 1 wherein the low temperature section (13) is divided into a plurality of sections, wherein a soot blower is provided at the inlet and outlet of each section.

5. Ammonium bisulfate control condensing system of claim 1 wherein the ash removal devices include sonic ash blowers (15) and steam ash blowers (16).

6. The ammonium bisulfate controlled condensation system of claim 1 wherein the high temperature section (12) and the low temperature section (13) both employ H-finned tubes, wherein the ratio of the height to the outer diameter of the H-finned tubes is 2 or less, and the ratio of the fin pitch to the height in the H-finned tubes is 0.30 or more.

7. Ammonium bisulfate control condensation system according to claim 1, characterized in that the flue gas cooler (2) is arranged in a vertical section of the boiler back pass and that the flue gas passes the flue gas cooler (2) from top to bottom.

8. Ammonium bisulfate control condensation system according to claim 1, wherein the distance between adjacent acoustic soot blowers (15) is less than or equal to 1.5m and the distance between adjacent steam soot blowers (16) is less than or equal to 2 m.

9. A method for controlling condensation of ammonium bisulfate is characterized by comprising the following steps:

calculating the heat transfer index T ═ T_py-Xt_AWherein, t_pyIs the exhaust gas temperature at the outlet of the air preheater (1), X is the X ratio of the air preheater (1), t_AWhen the temperature of the air at the outlet of the air heater (7) is higher than the design index T of the outlet of the air preheater (1)⁰When it is, thenWhen the heat exchange performance of the air preheater (1) is poor, the soot blower is used for carrying out soot cleaning treatment on the flue gas cooler (2); when T is less than T⁰When the air preheater is used, the heat exchange performance of the air preheater (1) is normal;

when the resistance of the air preheater (1) exceeds a set resistance value, the air temperature at the outlet of the air heater (7) is increased, the smoke temperature at the outlet of the air preheater (1) is increased, and the resistance of the air preheater (1) is reduced;

when the resistance of the air preheater (1) reaches a set resistance value, the air temperature at the outlet of the air heater (7) does not need to be continuously increased, and the air temperature index W is calculated to be a (t)_A-t_A ⁰)-b(t_y-t_y ⁰) When W is larger than 0, the air temperature is increased, and when W is smaller than 0, the air temperature is decreased, wherein t_AIs the actual wind temperature, t_A ⁰To design the wind temperature, t_yIs the actual flue gas temperature t at the outlet of the flue gas cooler (2)_y ⁰The design flue gas temperature at the outlet of the flue gas cooler (2) is represented by a, the influence coefficient of the air temperature at the outlet of the air heater (7) on the coal consumption of the unit power supply is represented by a, and the influence coefficient of the flue gas temperature at the outlet of the flue gas cooler (2) on the coal consumption of the unit power supply is represented by b.

10. The method of claim 9, wherein T is T⁰＝t_py ⁰-X⁰t_A ⁰，t_py ⁰For the design exhaust gas temperature, X, at the air preheater (1)⁰Design X ratio, t for air preheater (1)_A ⁰The designed air temperature at the outlet of the air heater (7).

Technical Field

The invention belongs to the technical field of generator sets, and relates to a system and a method for controlling condensation of ammonium bisulfate.

Background

The ultra-low emission policy requires that the concentration of dust at the outlet of the chimney is not more than 10mg/m³NOx concentration of not more than 50mg/m³，SO₂The concentration is not more than 35mg/m³The method contributes to the power for winning the blue sky guard war and plays a role in the meter rate for the ultra-low emission reconstruction of the non-electric industry. The denitration system basically adopts SCR technology or SNCR + SCR technology, and utilizes ammonia to reduce NOx in the flue gas into N₂When the ammonia can not completely react, the ammonia can escape, and the escaped ammonia and SO in the flue gas₃The reaction will form ammonium bisulfate, significantly increasing the viscosity of the fly ash. When ammonia slip exceeds 3ppm, the air preheater at the tail will be at risk of plugging.

Due to poor coal quality, unstable coal quality and large load change range of a thermal power plant in China, the phenomenon that the ammonia escape of a unit exceeds standard is common, some of the ammonia escape exceeds 10ppm, the air preheater at the tail part is blocked, the resistance of the air preheater exceeds 3000Pa when the air preheater is serious, and some of the ammonia escape exceeds even no load of the unit.

The currently adopted methods are ammonia injection optimization adjustment, air preheater modification or dual medium soot blowing. The ammonia escape of the unit can be reduced in a short time by optimizing and adjusting the ammonia injection, but the effect is reduced after the unit is changed into load and coal types. After the air preheater is transformed, the cold end adopts the heat exchange plate of big passageway, can lead to air preheater export flue gas temperature to rise, and boiler efficiency reduces, and long-time running resistance is still higher. The double-medium soot blowing adopts high-pressure water and steam soot blowing, the heating surface can be damaged due to high soot blowing frequency, and the resistance can be further improved.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides an ammonium bisulfate condensation control system and method, which can reduce the resistance of an air preheater and the exhaust gas temperature and reduce the power supply coal consumption of a unit.

In order to achieve the aim, the ammonium bisulfate condensation control system comprises a flue gas cooler, a fan heater, an air preheater, a flue gas cooler, a No. N low-pressure heater, a No. N-1 low-pressure heater and a No. N-2 low-pressure heater, wherein the air preheater and the flue gas cooler are sequentially arranged in a flue at the tail part of a boiler along the flow direction of flue gas;

the water inlet of the flue gas cooler is communicated with the water outlet of the booster pump, the water inlet of the booster pump is respectively communicated with the water inlet of the No. N low-pressure heater and the water outlet of the No. N-1 low-pressure heater, the water inlet of the No. N-1 low-pressure heater is communicated with the water outlet of the No. N-1 low-pressure heater, the water inlet of the No. N-2 low-pressure heater is communicated with the water outlet of the No. N-1 low-pressure heater, and the water outlet of the flue gas cooler is communicated with the water outlet of the No. N-2 low-pressure heater;

the air outlet of the air heater is communicated with the air inlet of the air preheater;

and a plurality of soot blowers are arranged in the flue at the tail part of the boiler, and each soot blower is just opposite to the flue gas cooler.

Still include the flue gas processing system, wherein, the flue gas processing system includes electrostatic precipitator, draught fan, desulfurizing tower and chimney, and wherein, the export of boiler afterbody flue is linked together with the chimney through electrostatic precipitator, draught fan and desulfurizing tower in proper order.

The flue gas cooler is divided into a high-temperature section and a low-temperature section, wherein soot blowers are arranged at an inlet and an outlet of the high-temperature section and an inlet and an outlet of the low-temperature section.

The low temperature section is divided into a plurality of sections, wherein, the entrance and exit of each section are provided with a soot blower.

The ash remover comprises a sound wave ash blower and a steam ash blower.

The high-temperature section and the low-temperature section both adopt H-shaped finned tubes, wherein the ratio of the height to the outer diameter of the H-shaped finned tube is less than or equal to 2, and the ratio of the pitch to the height of fins in the H-shaped finned tube is more than or equal to 0.30.

The flue gas cooler is arranged in the vertical section of the tail flue of the boiler, and the flue gas passes through the flue gas cooler from top to bottom.

The distance between the adjacent sound wave soot blowers is less than or equal to 1.5m, and the distance between the adjacent steam soot blowers is less than or equal to 2 m.

The ammonium bisulfate condensation control method comprises the following steps:

calculating the heat transfer index T ═ T_py-Xt_AWherein, t_pyIs the exhaust gas temperature at the outlet of the air preheater, X is the ratio X of the air preheater 1, t_AThe temperature of air at the outlet of the air heater is determined when T is greater than the design index T of the outlet of the air preheater⁰If the heat exchange performance of the air preheater 1 is poor, ash removal treatment is carried out on the flue gas cooler by using the soot blower; when T is less than T⁰And when the air preheater is used, the heat exchange performance of the air preheater is better.

When the resistance of the air preheater exceeds a set resistance value, the air temperature at the outlet of the air heater is increased, the smoke temperature at the outlet of the air preheater is increased, and the resistance of the air preheater is reduced;

when the resistance of the air preheater reaches a set resistance value, the air temperature at the outlet of the air heater does not need to be continuously increased, and the air temperature index W is calculated to be a (t)_A-t_A ⁰)-b(t_y-t_y ⁰) When W is larger than 0, the air temperature is increased, and when W is smaller than 0, the air temperature is decreased, wherein t_AIs the actual wind temperature, t_A ⁰To design the wind temperature, t_yIs the actual flue gas temperature at the outlet of the flue gas cooler, t_y ⁰The design smoke temperature at the outlet of the smoke cooler is represented by a, the influence coefficient of the air temperature at the outlet of the air heater on the coal consumption of the unit power supply is represented by a, and the influence coefficient of the smoke temperature at the outlet of the smoke cooler on the coal consumption of the unit power supply is represented by b.

T⁰＝t_py ⁰-X⁰t_A ⁰，t_py ⁰Design exhaust gas temperature, X, for air preheater⁰Design X ratio, t for air preheater_A ⁰The design wind temperature of the outlet of the air heater.

The invention has the following beneficial effects:

when the ammonium bisulfate condensation control system and the method are specifically operated, the average wall temperature of the cold end of the air preheater is increased by using the air heater, so that the condensation of ammonium bisulfate is reduced, ash removal measures are taken for the flue gas cooler, the influence of ammonium bisulfate ash deposition is eliminated by the ash blower, meanwhile, the heat transfer performance of the air preheater is evaluated by the index T, and when the heat transfer performance of the air preheater is poor, the air temperature at the outlet of the air heater is increased. When the air temperature at the outlet of the air heater is adjusted, the aim of the highest average wall temperature at the cold end of the air preheater is fulfilled by using the index W under the condition of ensuring that the coal consumption of the unit for supplying power is not reduced, the resistance of the air preheater is reduced, the efficiency of the unit is improved, and the coal consumption of the unit for supplying power is reduced.

Drawings

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

fig. 2 is a schematic structural view of the flue gas cooler 2 according to the present invention.

Wherein, 1 is an air preheater, 2 is a flue gas cooler, 3 is an electric dust remover, 4 is a draught fan, 5 is a desulfurizing tower, 6 is a chimney, 7 is a fan heater, 8 is a number N-2 low-pressure heater, 9 is a number N-1 low-pressure heater, 10 is a number N low-pressure heater, 11 is a booster pump, 12 is a high-temperature section, 13 is a low-temperature section, 14 is an overhaul channel, 15 is a sound wave soot blower, and 16 is a steam soot blower.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments, and are not intended to limit the scope of the present disclosure. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

There is shown in the drawings a schematic block diagram of a disclosed embodiment in accordance with the invention. The figures are not drawn to scale, wherein certain details are exaggerated and possibly omitted for clarity of presentation. The shapes of various regions, layers and their relative sizes and positional relationships shown in the drawings are merely exemplary, and deviations may occur in practice due to manufacturing tolerances or technical limitations, and a person skilled in the art may additionally design regions/layers having different shapes, sizes, relative positions, according to actual needs.

Referring to fig. 1, the ammonium bisulfate condensation control system of the present invention described with reference to fig. 1 includes a fan heater 7, an air preheater 1, a No. N low pressure heater 10, a No. N-1 low pressure heater 9, a No. N-2 low pressure heater 8 and a flue gas treatment system, wherein the flue gas cooler 2 and the air preheater 1 are both located in a flue at the tail of a boiler;

the water inlet of the flue gas cooler 2 is communicated with the water outlet of the booster pump 11, the water inlet of the booster pump 11 is respectively communicated with the water inlet of the No. N low-pressure heater 10 and the water outlet of the No. N-1 low-pressure heater 9, the water inlet of the No. N-1 low-pressure heater 9 is communicated with the water outlet of the No. N low-pressure heater 10, the water inlet of the No. N-2 low-pressure heater 8 is communicated with the water outlet of the No. N-1 low-pressure heater 9, and the water outlet of the flue gas cooler 2 is communicated with the water outlet of the No. N-2 low-pressure heater 8.

The air outlet of the air heater 7 is communicated with the air inlet of the air preheater 1, and the flue at the tail of the boiler is communicated with the inlet of the flue gas treatment system.

The flue gas treatment system comprises an electric dust collector 3, an induced draft fan 4, a desulfurizing tower 5 and a chimney 6, and an outlet of the flue at the tail part of the boiler is communicated with the chimney 6 through the electric dust collector 3, the induced draft fan 4 and the desulfurizing tower 5 in sequence.

The heat sources of the air heater 7 are hot water output by the flue gas cooler 2 and hot water or steam output by the low-pressure heater;

the air inlet of the air heater 7 is communicated with a blower.

The flue gas cooler 2 is arranged in a vertical flue, and flue gas flows through the flue gas cooler 2 from top to bottom.

The flue gas cooler 2 adopts an H finned tube, the ratio of the height of the H finned tube to the outer diameter of the H finned tube is less than or equal to 2, and the ratio of the pitch of the fins in the H finned tube to the height of the fins is more than or equal to 0.30.

The flue gas cooler 2 is divided into a high-temperature section 12 and a low-temperature section 13, the number of the pipe rows of the high-temperature section 12 along the flue gas direction is less than or equal to 8, when the number of the pipe rows of the low-temperature section 13 along the flue gas direction is greater than 12, the low-temperature section 13 is divided into a plurality of sections, and the number of the pipe rows of each section along the flue gas direction is less than or equal to 12.

An overhaul channel 14 is arranged between the high-temperature section 12 and the low-temperature section 13, the width of the overhaul channel 14 is more than or equal to 0.8m, and when the low-temperature section 13 is divided into a plurality of sections, the overhaul channel 14 is also arranged between two adjacent sections.

The sound wave soot blowers 15 and the steam soot blowers 16 are respectively arranged at the inlet and the outlet of the high temperature section 12 and the inlet and the outlet of the low temperature section 13, when the low temperature section 13 is divided into a plurality of sections, the sound wave soot blowers 15 and the steam soot blowers 16 are respectively arranged at the inlet and the outlet of each section, wherein the distance between the adjacent sound wave soot blowers 15 is less than or equal to 1.5m, and the distance between the adjacent steam soot blowers 16 is less than or equal to 2 m.

The steam soot blower 16 adopts a semi-telescopic type, and the sound power of the sound wave soot blower 15 is more than or equal to 150 dB.

The inlet of the flue gas cooler 2 is also provided with a flow guide plate.

The control process of the invention is as follows:

using T ═ T_py-Xt_ATo determine the heat transfer performance of the air preheater 1, wherein t_pyIs the exhaust gas temperature at the outlet of the air preheater 1, X is the X ratio and t of the air preheater 1_AWhen the temperature of air at the outlet of the air heater 7 is higher than the design index T of the outlet of the air preheater 1⁰When, T⁰＝t_py ⁰-X⁰t_A ⁰，t_py ⁰Design exhaust gas temperature, X, for air preheater 1⁰Design X ratio, t for air preheater 1_A ⁰Designing the air temperature at the outlet of the air heater 7, which indicates that the heat exchange performance of the air preheater 1 is poor, and performing ash removal treatment on the air preheater 1; when T is less than T⁰And when the air preheater is used, the heat exchange performance of the air preheater 1 is better.

If the resistance of the air preheater 1 exceeds a set resistance value, the air temperature at the outlet of the air heater 7 is increased, the smoke temperature at the outlet of the air preheater 1 is increased, and the resistance of the air preheater 1 is reduced.

When the resistance of the air preheater 1 reaches the set resistance value, the air temperature at the outlet of the air heater 7 does not need to be continuously increased, and W is equal to a (t)_A-t_A ⁰)-b(t_y-t_y ⁰) The air temperature at the outlet of the air heater 7 is controlled by the index (t), namely when W is more than 0, the air temperature is increased, and when W is less than 0, the air temperature is reduced, wherein t_AIs the actual wind temperature, t_A ⁰To design the wind temperature, t_yIs the actual flue gas temperature, t, at the outlet of the flue gas cooler 2_y ⁰The design flue gas temperature at the outlet of the flue gas cooler 2; a is the influence coefficient of the air temperature at the outlet of the air heater 7 on the coal consumption of the unit power supply, and is obtained by optimization test or calculation; and b is the influence coefficient of the flue gas temperature at the outlet of the flue gas cooler 2 on the power supply coal consumption of the unit.

During actual operation, utilize air heater 7 to improve the wind temperature of air heater 1 entrance, in order to improve the exhaust gas temperature in air heater 1 exit, then improve the average wall temperature of air heater 1 cold junction, shift partial ammonium bisulfate condensation zone to flue gas cooler 2's region, reuse flue gas cooler 2 to handle ammonium bisulfate deposition, utilize steam soot blower 16, sound wave soot blower 15, finned tube design and heat exchanger arrangement mode carry out the deashing to flue gas cooler 2, set for the index T of judging air heater 1 heat transfer performance, when index T is relatively poor, then improve the wind temperature in air heater 7 exit, reduce air heater 1's resistance, improve air heater 1's heat transfer performance. When the air temperature at the outlet of the air heater 7 is increased, the boiler efficiency is improved, and simultaneously, the flue gas is dischargedThe smoke temperature at the outlet of the cooler 2 is increased, the coal consumption of the unit is increased, and therefore the invention passes W ═ a (t)_A-t_A ⁰)-b(t_y-t_y ⁰) The target of (1) achieves the purpose of the highest average wall temperature of the cold end of the air preheater under the condition of ensuring that the coal consumption of the unit for supplying power is not reduced, effectively reduces the resistance of the air preheater 1 and improves the efficiency of the unit.