鍋爐低氮燃燒器改造后低負荷汽溫無法達設計值

1、設備簡介

1.equipment introduction

某廠SG1025/17.4-M847型鍋爐為上海鍋爐廠制造亞臨界、一次中間再熱、自然循環、固態排渣爐，鍋爐為∏型布置，采用平衡通風，四角切向燃燒，配四臺低速鋼球磨中儲式制粉系統。設計煤種為貧瘦煤。鍋爐50%額定負荷滑壓工況下設計過熱汽溫540，再熱汽溫515℃。

SG1025/17.4 M847 type boiler at a factory for manufacturing subcritical boiler plant in Shanghai, a reheat, natural circulation, solid-state slag furnace, boiler of ∏ type is decorated, USES the balanced ventilation, tangential firing, with four reservoir type in low speed ball mill coal pulverizing system. Design coal for zhengzhou area lean coal. 50% rated load sliding pressure boiler design superheated steam temperature of 540, under the condition of reheat steam temperature 515 ℃.

主燃燒器一次風及二次風逆時針方向布置，雙切圓直徑大小為719/?686。三次風順時針方向布置，與一、二次風方向主軸反偏10度。SOFA燃燒器順時針方向布置，與一、二次風方向主軸反偏6度。三次風與SOFA風共同起消旋風作用。

The primary and secondary air of the main burner are arranged counterclockwise. 719 /? 686. Three times the wind clockwise direction layout, with one, two times the wind direction of the main axis back 10 degrees. SOFA burner is arranged in a clockwise direction, 6 degrees backward from the main axis in the direction of first and second wind. Three times wind and SOFA wind together play the role of anti - cyclone.

主燃燒器一、二次風噴口與SOFA燃燒器噴口均裝有自動垂直擺動裝置。一、二次風噴口可上下擺動±30度，擺動機構分為上、下兩組。SOFA風噴口還可以以手動方式左右擺動±15度。

2、1#機組150MW低負荷工況下的汽溫問題及原因分析

2.Analysis of steam temperature problem and its causes in 150MW low load condition of unit 21

鍋爐低氮燃燒器改造后主要存在單套制粉運行時主汽溫度、再熱汽溫度低，但后屏過熱器管壁超溫，一級減溫水量增加的現象。通過試驗發現當在150MW時如果投運兩套制粉系統，如A、C或B、C制粉系統汽溫可以達到536℃～538℃，且后屏不超溫，過熱器有減溫水。當投單套制粉系統，過熱汽溫最低時達504℃左右，再熱汽溫低達495℃左右，但是過熱器一級減溫水量卻達到近40t/h，前屏也經常超溫。

The main steam temperature and reheat steam temperature of a single set of pulverized powder are low after the modification of the boiler low nitrogen burner. Through the study found that when in 150 mw if put two bearing powder system, such as A, C or B and C pulverizing system steam temperature can reach 536 ℃ ~ 538 ℃, and the screen is not overtemperature, superheater with warm water. When single bearing powder system, superheated steam temperature when a minimum of 504 ℃ or so, low reheat steam temperature of 495 ℃ or so, but the superheater level of desuperheating water flow to nearly 40 t/h, front panel also often overtemperature.

分析單套制粉系統運行過、再熱汽溫偏低原因為：

The reasons for the low reheat steam temperature of the single set pulverized powder system are as follows:

(1)當投運兩臺磨時，燃燒器四角能夠兩兩相對投運三次風，作為反切消旋功能的三次風流場相對均勻，爐膛出口煙氣流場偏差較小，屏底超溫較好。

(1) when the operation of two grinding, the corners of the burner to three times the wind two relative was put into operation, the methods of three wind field despun function is relatively uniform, furnace exit deviation is small, smoke flow in the bottom of the screen overtemperature is better.

(2)當投運單臺磨時，燃燒器四角只能夠投運一個對角三次風而無法形成有效的消旋流場，再者對角三次風的氣固兩相流速可能不均勻而有可能導致流場的紊亂，使得爐膛出口煙氣流場偏差增加，引發屏底超溫，過熱器減溫水大量增加，屏后煙溫降低，限制了過熱汽溫及再熱汽溫增加。

(2) when cast waybill grinding machine, three times in the corners of the burner can only put a diagonal wind to form effective despun flow field, moreover diagonal three times the wind of the gas-solid two phase flow rate may be uneven and could lead to disorder, the flow field in the furnace exit deviation of smoke flow in increasing, lead to the bottom of the screen overtemperature, superheater reduction with warm water, screen after smoking temperature is reduced, limits the superheated steam temperature and reheat steam temperature increase.

(3)相對于投運兩臺磨，單臺磨投運時燃燼區煤粉濃度低于兩臺磨投運時的工況，屏底煙氣溫度也相應較低。

(3) compared with the two mills, the coal powder concentration in the embers area in the single mill is lower than that in the two mills, and the flue gas temperature at the bottom of the screen is lower.

3、治理方案及效果

3. Governance scheme and effect

針對低負荷單套制粉系統主、再熱汽溫偏低問題原因，提出以下治理措施：

In order to solve the problem of low main and reheat steam temperature of low-load single set pulverized powder system, the following measures are proposed:

(1)提高爐膛送風量，可提高煙氣流量。

(1) to increase the air flow in the furnace can increase the smoke flow.

(2)調整SOFA風左右擺角，中、下層SOFA風已經調成與一次風及二次風一致，均為逆時針方向布置，上層SOFA風與一次風及二次風反切。配合主燃燒器消旋二次風及其它二次風比例以控制爐膛出口煙氣溫度及煙氣量的偏差，控制屏過金屬溫度兩側無偏差時盡量減少減溫水量提高汽溫。

(2) adjust the left and right Angle of SOFA wind, and the middle and lower SOFA wind has been adjusted to be consistent with primary and secondary wind, both of which are arranged counterclockwise. The upper SOFA wind is opposite to primary and secondary wind. Cooperate with the main burner despun secondary air and other secondary air ratio of air to control the furnace exit flue gas temperature and smoke deviation, control panel metal temperature without deviation on both sides to minimize desuperheating water flow to improve the steam temperature.

(3)在以上基礎上汽溫仍低時，采用調節主燃燒器擺角向上;適當啟動部分D層燃燒器;減少磨機再循環率，提高三次風量;盡量提高C、D層給粉機轉速，降低A或B層給粉機轉速等方式亦可提高汽溫。

(3) when the temperature of the above foundation is still low, the swing Angle of the main burner is adjusted upwards; Properly start part D layer burner; Reduce the recirculation rate of the mill and increase the air volume three times. The steam temperature can be increased by increasing the speed of layer C and layer D feeder as much as possible, and decreasing the speed of layer A or layer B feeder.