Guodian Minquan Power Plant (Modification of Raw C

Guodian Minquan Power Plant

 (Modification of Raw Coal Bunker Due to Coal blockage) 

  Situated at Minquan County, Henan Province, Guodian Minquan Power Co., Ltd. has 3.2 million kw planned capacity of the Power Plant and was developed into the first one million kw power plant built and controlled by China Guodian Corporation in Henan Province. Two sets of Phase-I 600000 KW domestic supercritical coal-fired units project commenced on September 26, 2006 and No. 1 and No. 2 units were put into formal production for power generation on August 23, 2008 and November 6, 2008 respectively, realizing the target of “double completion” in 2008.

  Raw coal bunker of this plant is steel-structure cone bunker and has been plagued by serious coal blockage after it is put into production in 2008 (fig. 1). As shown in the figure, the coal bunker has serious beating trace or even encounters coal interruption under serious circumstances.

  Some Henan company has installed rotary dredging device on the upper side of slide plate gate (Fig. 2). However, rotary dredging device fails to implement dredging at the discharging segment of raw coal bunker and scraper used for dredging is welded to internal wall of discharging segment of raw coal bunker, causing new blockage points at the place where coal blockage easily occurs. And product technology and process are not mature and it fails to realize the dredging effects after the installation. After nearly half a year of maintenance and improvement, it still fails to work as expected and finally Minquan Power Plant decided to dismantle it. Afterwards, the Power Plant had to install traditional dredging equipment, such as air cannon and vibrator, which still depend on manual work to strike bunker wall though achieving certain dredging effects.

  At the beginning of 2014, Minquan Power Plant has determined to implement blending combustion of low-price coal slime at large proportion to lower operating costs and improve economic benefits. However, as high water contents and large viscosity in the coal slime give rise to frequent coal blockage or interruption in the raw coal bunker, previous dredging device can’t meet demands any more and on-site first-aid repair mainly relies upon working personnel, consuming too much labor of professional staff, affecting the on-load capacity of boiler seriously and bringing great potential safety hazard to Minquan Power Plant. To eliminate the serious coal blockage as soon as possible, boiler professionals of Minquan Power Plant have conducted large-scale investigation and survey over dredging device market, visited several power plants on site and finally determined to choose activated dredging device manufactured by our Company. After the actual measurement and analysis over raw coal bunker of Minquan Power Plant, our technicians found that on-site coal blockage mainly occurs within 2m below or above the slide plate gate. This area is characterized in that bunker section is in descending order, resulting in larger upward frictional resistance and internal extrusion force of the coal flow and causing caking and adherence. In addition, after the occurrence of coal blockage at the lower end, blockage position will extend upwards until reaching the upper part of raw coal bunker, which is the main reason for caking in the segment with large diameter at the upper part. Moreover, increased change to water contents and particle size of materials after the blending combustion of coal slime has also worsened the coal blockage.

  After the communication and exchange of opinions between technical department of our Company and boiler professionals of the Power Plant, we decided to add a complete set of activated dredging device we manufactured. This device is divided into upper, middle and lower parts; the upper part is the bunker rotary dredging device and transition bunker that has the maximum diameter of 1.5m and connected to raw coal bunker through streamline transition section properly; the middle part is special-purpose slide plate gate independently designed and developed by our Company; the lower part is the scraper rotary dredging device playing the role of dredging the coal dropping pipe. In the recent years, more and more power plants choose to implement blending coal combustion and set higher requirements on the functions of coal bunker dredging device. Thanks to analysis over coal blockage at many power plants over the past years, our Company has designed and manufactured the complete set of activated dredging device, broken the limitation of single rotary bunker on dredging of the rear end of coal bunker through three-segment structure of lower, middle and upper parts and achieved the seamless joint between coal dropping pipe and lower part of raw coal hopper, which can perform all-round dredging over serious coal blockage area from the area above coal feeder to upper part of rotary bunker and ensure the smooth coal flowing and put an end to coal interruption.

  Our Company has finished the installation of activated dredging device at B and D coal bunkers of No. 1 furnace for Minquan Power Plant successfully prior to March 25 and March 29 respectively (Fig. 3) and anticipated number of the Power Plant coal slime used for blending combustion at that month is 35000t. As soon as being put into operation, B and D bunkers have undergone test about blending combustion of coal slime, which has seen obvious dredging effects and recognized by all the employees of the Power Plant unanimously. Thanks to timely installation of dredging device, the Power Plant has completed the blending combustion task successfully and two bunkers of dredging device added have finished the blended combustion of nearly 10000t coal slime in just a few days, saving nearly RMB 600000 of fuel coal expenses for the Power Plant indirectly. Furthermore, the Power Plant has decided to add 6 more activated dredging devices and installed them properly by the end of June. For the time being, 8 devices are under normal operating condition, thus providing full guarantee for Minquan Power Plant to complete coal slime blended combustion plan.

AttachmentEvaluation of Using Effects by Customers