Verify Steam Balance

It is a daunting task to put together overall steam balance as it may require weeks or months of time to develop such a comprehensive steam balance based on operating data, modeling, correlations, and experience. In the end of this endeavor when putting everything together, you may punch your fist to the sky and say 1 got it, baby  

It will be very understandable if you are exuberant and happy after you build the steam balance. It gives you a sense of pride when you visualize the complex steam network of energy generation, distribution, and demand at a glance. 

Your colleagues may ask you Is it ready to be applied for operational supervision and opportunity assessment It is a million dollar question as the stake on the table is high. Opportunities for a steam and power system are worth millions of dollars. 

For the control valve at hand, the ratio of the inlet pressure (624.7psia) and outlet pressure (164.7 psia) is only 26%. Thus, the choke flow equation (16.10) is applied to give the letdown flow of 71.2 Klb/h based on the value position at 75% openning. The choke flow rate is smaller than the nonchoke flow. By correcting this mistake, there is still a large imbalance in the HP header. What else went wrong The search continues. 

2 Task 2 Inspect the Control Valve for Erosion The field inspection indicated severe erosion occurring. This imphes that the correlation in DCS could give an underestimate of actual letdown flow. To prove this suspicion, meter calibration was conducted for each HP user and then the letdown flow was back-calculated to give a letdown flow of 97 klb/h for the meter reading of 84 klb/h. A factor was added to the DCS correlation for modeling the control valve to reflect the erosion. At the same time, a maintance order was requested for fixing the problem. 

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We will leam two things from this chapter. The first is how to build a complete steam balance from scratch illustrated by a real example, while the second is to verify the balance to make it more trustworthy. 

Step 3 Calculate DALP and Revise the Balances 29 klb/h of DA LP steam was assumed previously based on experience and it is verified here based on the heat and mass balances around the deaerator ... 

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