中频电炉 | 节能减排指南
一、整流變壓器
確保變壓器供應商了解變壓器的負載類型，知道中頻電源的變壓器負載是一個整流型負載，應該維持在變壓器銘牌所標主的效率。通常我們通過K系數來衡量變壓器的諧波引起的損耗，通常6脈沖的整流變壓器的K系數爲K-9，而12脈沖的整流變壓器的K系數是K-4.通常情況下整流變壓器的效率達到99%是完全有可能的，通常情況下我們最低取98.5%。
二、變壓器進線
變壓器二次和中頻電源的連接線的能量損耗是非常小的，考慮正常的電流密度來考慮母排及電纜，每米的能量損耗爲6/V%。這裏的V是就是中頻電源的進線電壓，我們比方說，變壓器的一次電壓爲10KV，二次電壓爲575V，最好的就是變壓器離電源盡可能的近。在任何情況下，最大限度的縮短變壓器和電源之間的距離是有利于降低電源側的能量損耗的。
比如說：變壓器的二次575V，20米的距離就有0.2%的損耗。
三、中頻電源
中頻電源的損耗主要取決于逆變器的類型（電壓型/電流型，IGBT/SCR）及頻率。
下面是<700Hz時，主要元件損耗的一個比較：
|
|
SCR |
IGBT |
|
|
Series |
Parallel |
Series |
Parallel |
|
DC Choke |
1.1% |
1.9% |
1.1% |
1.9% |
|
didt chokes |
0.9% |
0.45% |
0% |
0% |
|
Devices |
0.8% |
0.58% |
1.6% |
1.2% |
|
(Rel#) |
(2) |
(1) |
(4) |
(2) |
|
Total |
2.8% |
2.9% |
2.7% |
3.1% |
通過上面的比較，有些相對比較小的差別，在低頻的工作時，IGBT的損耗相對于SCR要高，應爲在同樣的電流情況下，IGBT的數量要多。但是隨著頻率的增加，SCR的額定容量下降，通常來說在2KHz以上，IGBT變得更有優勢。
四、諧振電容
諧振電容的損耗通常我們考慮爲大約~0.15W/100kVAr。不管是串聯諧振還是並聯諧振，對于諧振電容來說都是用于補償線圈滯後的功率因數，所以損耗來說也沒有太大的區別。
然而，在實踐中用大容量的電容更有能耗優勢，因爲大容量的電容的使用，能夠減小電容櫃的尺寸，減少電容器的數量，當然也好減少連接電容器母排的數量，所以能耗相對于更低。
五、輸出母排
我們用正常的電流密度來考慮，典型的損耗可以用下面的數據來估算：
對于水冷母排來說每米的損耗爲0.1%
對于風冷母排來書每米的損耗爲0.065%
所以，單從能量損耗的角度來考慮，盡可能減少逆變輸出和電爐之間的距離以及水冷電纜的長度是尤爲重要的。雖然風冷的母排有更高的效率，但是風冷母排運行時也需要更多的母排及更大的冷卻空間。翻倍數量的母排並不能夠降低一般的損耗。下面很明顯的能夠說明：
铜母排在40摄氏度时的电阻率为1.86u-ohm cm（这里假设冷却水温度低于摄氏40度）
铜母排在85摄氏度时的电阻率为2.16u-ohm cm（这里假设环境温度为35摄氏度）
用一块水冷母排时，对应的能量损耗为1.86 x 1^2 = 1.86
用两块风冷母排时，对应的能量损耗为2.16*((1/3)^2 + (2/3)^2) = 1.20因为用两块母排载流量并不是50/50,而是33/67。
六、水冷電纜
通常情況下：水冷電纜的損耗爲： 0.23%/m
水冷電纜的能量損耗要比輸出母排高很多，所以設計時，盡可能的減小水冷電纜的長度尤爲重要， 增加水冷電纜的數量對減小能耗也是有幫助的，但是通常情況下，傾爐時過多的水冷電纜是不太實際的。
七、電爐部分
電路部分就是能量損耗最大的部分，但是可以通過下列手段能夠做到節能：
--- 使用好的，幹淨的爐料
--- 組織好的爐料及造型，提高爐子的使用率
--- 養成良好的蓋爐蓋的習慣
--- 維護好爐襯，避免搭橋，不要在爐襯太薄是繼續使用
7.1 電氣損耗
感應線圈的電氣效率主要取決于線圈形狀、金屬的電阻率和頻率，在有效線圈的直徑和高度比爲1，熔池的內徑爲線圈內徑的0.75-0.8，運行頻率在200到300Hz時，線圈部分的電氣損耗爲：
線圈的電氣損耗：約18%
磁轭及短路環的損耗：約爲1.5%
總的損耗爲：19.5%
以上的計算都是基于線圈銅管的截面積是矩形管，線圈的占空比大于0.8的設計，矩形管的線圈的要圓管的線圈高出3%左右。
7.2 熱損耗
熱損耗主要取決于爐襯材料的導熱系數，但是對于鑄鐵應用案例，通常都是用石英砂爐襯，
带炉盖，功率密度在500KW每吨的熔化炉，热损耗在10.6% - 2.3%（1吨-25吨）
带炉盖，功率密度在750KW每吨的熔化炉，热损耗在7.1% - 1.5%
不带炉盖，功率密度在500KW每吨的熔化炉，热损耗在24.2% - 6.9%（1吨-25吨）
不带炉盖，功率密度在750KW每吨的熔化炉，热损耗在16.1% - 4.6%
通過上面的比較，我們能夠很明顯的看出高功率密度帶爐蓋的設計能夠提高效率，在滿路鐵水保溫或升溫時有明顯的優勢。
7.3 電氣損耗及熱損耗的綜合考慮
通過下列表格的對比，我們看出中頻熔化電爐的熱損耗和電氣損耗對總體損耗的影響是非常有趣的。
下面的曲線表明，有關爐襯的搗築，當我們增加爐襯的厚度來提高爐襯的壽命的同時減低電爐的效率。當減薄爐襯的厚度來提高電電爐的效率時，導致的後果就是爐襯的壽命縮短。過去的經驗告訴我們，當爐襯的厚度被燒損到設計厚度的2/3時就應該更換新的爐襯了，小爐子的爐膛內徑和線圈內徑的比爲0.75-0.83，大爐子在0.8-0.87爲電爐運行的最佳效率範圍。
八、其它輔助系統的損耗
在中頻感應電爐安裝時有幾套配套的輔助系統，他們包括下面幾個系統：
---冷卻系統
---液壓系統
---除塵系統
8.1 冷卻系統損耗
當電爐運行時水冷系統就會一直連續工作，在電爐停止運行後，冷卻系統會一直運行好幾個小時後直到電爐完全冷卻。
通常冷卻系統的形式有所不同（開路冷卻系統，閉路冷卻系統，蒸發式冷卻塔，幹式冷卻塔、節水型的）但是閉式冷卻塔系統在使用中最爲常見。通常有水泵，冷卻塔的噴淋泵，冷卻塔的風機組成，因爲循環水的流量和中頻電爐的功率成正比，水泵的功率也和流量成正比，所以我們可以認爲水泵的功率和中頻電爐的功率也是一個正比的關系。
冷卻系統的散熱能力和電爐的功率也是成比例的關系，所以冷卻塔運行所需的功率也是和電爐的功率成正比關系；下面是水泵功率 冷卻塔的運行功率和電爐功率的一個關系：
所以在一電一爐的系統中，冷卻系統設備的能耗占整個中頻電爐熔化系統的1.2%。
下面是一些減少能耗的方法：
-
確保冷卻塔風機控制的溫度開關正常工作，並且設定溫度值不會過低；
-
確保外循環補水的水質幹淨
-
確保冷卻塔噴淋管通暢，冷卻塔的盤管幹淨，維持較高的冷卻效率
-
確保冷卻塔的噴淋泵比冷卻塔的風機先開後關，避免冷卻塔的盤管結垢。
8.2 液壓系統損耗
液壓系統中液壓泵的大小和中頻電爐的大小有著直接的關系，保證兩分鍾的傾爐時間，液壓泵的大小大約爲電爐噸位數的3倍，比如說，10噸的電爐，液壓系統中液壓泵的功率爲30KW。
所以如果一個小時中液壓泵的運行時間爲10分鍾，電爐的功率密度爲500KW/噸，液壓系統的能耗占整個系統的0.1%，占系統功耗是非常小，但是在不需要使用液壓系統時應該及時關閉液壓系統。
8.3 电炉的吸尘装置损耗
由于吸塵裝置對于風量的需求，吸塵裝置風機的功率取決于電爐噸位的大小及什麽類型爐蓋的使用，還有熔化什麽樣的爐料的，（比方說，吸塵罩的風機功率比吸塵環需要大一倍。）通常來說，風機的功率大小和爐子噸位大小的立方根成比例。
基于吸塵環的計算，吸塵系統的能耗是這樣一個範圍：1噸的爐子吸塵系統的能耗爲系統的0.4%。而25噸爐子吸塵系統占整個熔化系統的0.14%。對于一對一的電爐的熔化系統，我們沒有太多節能工作可做，但是對于多電爐熔化系統，但爐子不需要吸塵裝置時應有相應的切換裝置。
"Excuse me," Arthur ventured, huskily, "did you wish to speak to me?" "What!" Balmayne cried, "were you mad enough to----." seventeen Christmas presents? I'm a Socialist, please remember; And to close the procession came more soldiers. For that fog the seaplane was making at full speed. It was no wonder that Spain, feeling the serious effects of this state of things, should resist it; and when she did so, and exerted an unusual degree of vigilance, then the most terrible outcries were raised, and wonderful stories were circulated of Spanish cruelties to our people beyond the Atlantic. At this time the Opposition got hold of one of these, and made the House of Commons and the nation resound with it. It was, that one Captain Robert Jenkins, who had been master of a sloop trading from Jamaica, had been boarded and searched by a Coastguard, and treated in a most barbarous manner, though they could detect no proof of smuggling in his vessel. He said that the Spanish captain had cut off one of his ears, bidding him carry it to his king, and tell his Majesty that if he were present he would treat him in the same manner. This story was now seven years old, but it was not the less warmly received on that account. It excited the utmost horror, and Jenkins was ordered to appear at the bar of the House of Commons on the 16th of March, to give an account of the outrage himself; and it would appear that both he and other witnesses were examined the same day. Jenkins carried his ear about with him wrapped in cotton, to show to those to whom he related the fact, and the indignation was intense. He was asked by a member how he felt when he found himself in the hands of such barbarians, and he replied, "I recommended my soul to God, and my cause to my country." The worthy skipper had probably been crammed with this dramatic sentiment by some of his clever Parliamentary introducers; but its effect was all the same as if it had been a genuine and involuntary expression of his own mind. Researches made at the Admiralty in 1889 proved that he really had lost an ear. Nevertheless, the whole army was dead beat and in the most deplorable condition when they entered Carlisle on the morning of the 19th. As the enemy did not appear, they rested that day and the following night, when they set forward again, leaving a fresh garrison. Cumberland was soon up before the walls, and they fired vigorously at him; but he sent off to Whitehaven and brought up six eighteen-pounders, with which, to their dismay, he began to play on their crumbling walls on the 29th. Next morning they hung out a white flag, and offered to capitulate; but Cumberland would hear of no terms except their surrendering on condition that they should not be put to the sword. At three o'clock in the afternoon both town and castle were surrendered, the garrison being shut up in the cathedral, and a guard set upon them. On the 3rd of January the Duke of Cumberland left the command to General Hawley, and hastened back to London, being summoned to defend the southern coast from a menaced landing of the French. In pursuance of this plan of the campaign, Prideaux and Johnson arrived before the fort of Niagara in the middle of July, which they found very strong, and garrisoned by six hundred men. Prideaux was soon killed by the bursting of a shell, but Johnson continued the siege with great ability, having to invest the fort on one hand, whilst he was menaced on the other by a mixed body of French and Indians, one thousand seven hundred in number, who came to relieve the fort. The attack upon him commenced with a terrible war-whoop of the Indians, which, mingling with the roar of the great cataract near, made the most horrible din imaginable. But this did not disconcert the English and their savage allies, who received them with such steady courage, that in less than an hour they were put to the rout in sight of their own garrison, and pursued for five miles with dreadful slaughter. The garrison thereupon capitulated, remaining prisoners of war. There, however, Sir William Johnson's career stopped. From various causes, not foreseen, he was not able to advance beyond the Ontario to unite with Amherst. That general had fully succeeded in taking Ticonderoga and Crown Point, but he found the French so strongly posted on an island at the upper end of Lake Champlain, that he was compelled to stop and build[134] boats to enable his army to reach and dislodge them; and it was not till October that he was ready to proceed, when he was driven back repeatedly by tempests, and compelled to go into winter quarters. "Some of you find Lieut. Bowersox, and bring him here," said Capt. McGillicuddy, sitting up, and beginning to twist a handkerchief around his thigh, to form a tourniquet. "Lieutenant, you all right?" The old man mounted into the seat, gathered up the rope lines, and chirruped to the horse to start. He hitched forward cautiously a little farther, to where he could peer through the bushes, being exceedingly wary not to repeat his opponent's mistake, and set their tops in motion. A rock protruding through the ground in front of him made an opening through which he could see, and also afforded a rest for his musket. He looked sharply, and at length was rewarded by seeing the gun-barrel come out by the side of the barked willow, rested on a bare limb, and apparently aimed at the hill beyond. He took a long breath to steady his nerves, stretched out his legs to make himself more at ease, pushed his musket forward until he got exactly the right poise, aimed about nine inches below the level of his opponent's gun-barrel, and a little to the left, drew his bead down to a hair's nicety in the hind sight, and pulled the trigger just as the rebel sharpshooter did the same. Both muskets seemed to flash at the same moment. The rebel sprang up through the willows and fell forward on his face. There was a vague hint that he had seen the face somewhere, but he dismissed it, then settled himself, and, busy with his own thoughts, pressed his face against the window, and tried to recognize through the darkness the objects by which they were rushing. They were all deeply interesting to him, for they were part of Maria's home and surroundings. After awhile the man appeared temporarily tired of billing and cooing, and thought conversation with some one else would give variety to the trip. He opened their lunch-basket, took out something for himself and his companion to eat, nudged Shorty, and offered him a generous handful. Shorty promptly accepted, for he had the perennial hunger of convalescence, and his supper had been interrupted. It was their regiment—the 200th Ind.; it was made up of the same companies, with the great majority of the men the same, but it was very far from being the 200th Ind. which crossed the Ohio River in September, 1862. "I should say he had a mighty strong breath, Monty," Shorty interrupted. He liked to break in on Monty's heroics. "Excuse me from havin' a 12pounder breathin' around me." "Yes, but d?an't m?ake him angry—he might beat you." "I used to be in the fancy," said the minister, "but five years ago the Lord challenged me, and knocked me out in the first round." "We shall talk further," said Holgrave: "in the mean time, we must consult for your own safety. If your father was a villein of this barony, it is not likely that the old steward, or the new one—the fiend Calverley—should forget you; and——"
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