The Effect of Excess Heat Utilization on the Production Cost of Cement

Industrial excess heat is a largely untapped resource that has the potential for external use that would be beneficial to the cement industry. Therefore, this work studied the excess heat utilization for the optimization of production cost in a cement plant within a period of three years. The study of plant layout in the selected plant in Nigeria (Ewekoro II Cement Plant of 200 tonnes/hour) was carried out to identify areas where excess heat is generated. The temperature and static pressure of precalciner, kiln, and cyclone were taken using a temperature probe, pitot tube, digital manometer, and light-emitting diode temperature reader. These parameters were used to obtain the mass flow rate and heat transfer needed for the heat energy analysis of the system. The kiln was maintained at constant tonnage per hour through a clinker truck weighed using the weighbridge. The result showed that the heat generated from the kiln was 577,640,260 MJ/hr. through excess air draft of 780,000 m3/hr (89.4%) at 250 °C and induced draft fan of 900,000 m3/hr at 350 °C. The result showed that excess heat can be utilized in pre-heater and air quenched cooler boilers, steam turbines and auxiliaries, and generators. The total estimated heat that could be saved amounted to 344,648,250 MJ with a total annual capacity of 2.25 million tonnes of cement. A saving of over two billion dollars could be achieved in production cost per year.

Application of space vector pulse width modulation algorithm based on programmable logic array in power system

In the traditional power system, the voltage regulation and frequency modulation control method used for boiler induced draft fan is limited in control accuracy. With the improvement of furnace pressure change accuracy, higher requirements are put forward for motor control algorithm. This paper studies permanent magnet synchronous motor (PMSM) as the executive part of induced draft fan servo control system, and adopts FOC control method based on space vector pulse width modulation (SVPWM). Firstly, the simulation model of SVPWM pulse width modulation algorithm is established by MATLAB to provide theoretical support for the subsequent debugging algorithm; When using FPGA to realize SVPWM modulation algorithm, FPGA has the advantages of high reliability and high real-time processing, which provides theoretical support and application guidance for the realization of high-precision motor control of boiler induced draft fan in power system.

Boiler retrofit improves efficiency and increases biomass firing rates

Domtar’s fluff pulp mill in Plymouth, NC, USA, operates two biomass/hog fuel fired boilers (HFBs). For energy consolidation and reliability improvement, Domtar wanted to decommission the No. 1 HFB and refurbish/retrofit the No. 2 HFB. The No. 2 HFB was designed to burn pulverized coal and/or biomass on a traveling grate. The steaming capacity was 500,000 lb/h from coal and 400,000 lb/h from biomass. However, it had never sustained this design biomass steaming rate. As the sole power boiler, the No. 2 HFB would need to sustain 400,000 lb/h of biomass steam during peak loads. An extensive evaluation by a combustion and boiler technologies supplier was undertaken. The evaluation involved field testing, analysis, and computational fluid dynamics (CFD) modeling, and it identified several bottle-necks and deficiencies to achieving the No. 2 HFB’s biomass steam goal. These bottlenecks included an inadequate combustion system; insufficient heat capture; excessive combustion air temperature; inadequate sweetwater con-denser (SWC) capacity; and limited induced draft fan capacity. To address the identified deficiencies, various upgrades were engineered and implemented. These upgrades included modern pneumatic fuel distributors; a modern sidewall, interlaced overfire air (OFA) system; a new, larger economizer; modified feedwater piping to increase SWC capacity; replacement of the scrubber with a dry electro-static precipitator; and upgraded boiler controls. With the deployment of these upgrades, the No. 2 HFB achieved the targeted biomass steaming rate of 400,000 lb/h, along with lowered stack gas and combustion air temperatures. All mandated emissions limit tests at 500,000 lb/h of steam with 400,000 lb/h of biomass steam were passed, and Domtar reports a 10% reduction in fuel firing rates, which represents significant fuel savings. In addition, the mill was able to decommission the No. 1 HFB, which has substantially lowered operating and maintenance costs.

ANALISA UNJUK KERJA INDUCED DRAFT FAN PLTU ASAM-ASAM UNIT 3 DAN 4

Throughout the year 2015, PLTU Asam Asam Unit 3 and 4’s Induced draft fans frequently having issues. These issues were affects customer’s elecricity consumption because of load generated from PLTU Asam Asam unit 3 and 4 is was decreased heavily, seldom made the unit shut down for maintenance. This issues was being discussed and investigated to find the source and solutian to fix it. After the investigation, it is found that fly ash who was being carried by flue gas through IDF was stuck to fan’s blade and create unbalance in its rotation. Next modification was applied to fly ash transmitter to make sure its operating continous because it has been stopped for a while. The effect of this modification is quite significant if we compare data from before and after modification, it can be see that derating and shutdown because of IDF problem is fewer than what it was before modification.