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Technical Inquiry PTC 4.1 - 1964 (R1991) Steam Generating Units

The document discusses questions regarding testing procedures for evaluating new coal burners on a steam generating unit according to testing standard PTC 4.1-1964. For question 1, it is recommended that the percentage used for unmeasured losses in the efficiency calculation be estimated individually for the baseline and post-retrofit tests rather than using the same value, as some losses could be affected by the new burners. For question 2, while PTC 4.1 specifies measuring gas temperature at the air heater outlet, it is acceptable to take the reading at the economizer outlet instead, to isolate the evaluation to the burners and not be affected by potential changes in air heater efficiency. Engineering judgment should be used

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66 views2 pages

Technical Inquiry PTC 4.1 - 1964 (R1991) Steam Generating Units

The document discusses questions regarding testing procedures for evaluating new coal burners on a steam generating unit according to testing standard PTC 4.1-1964. For question 1, it is recommended that the percentage used for unmeasured losses in the efficiency calculation be estimated individually for the baseline and post-retrofit tests rather than using the same value, as some losses could be affected by the new burners. For question 2, while PTC 4.1 specifies measuring gas temperature at the air heater outlet, it is acceptable to take the reading at the economizer outlet instead, to isolate the evaluation to the burners and not be affected by potential changes in air heater efficiency. Engineering judgment should be used

Uploaded by

Daniel Alvarez
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
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1997 TECHNICAL INQUIRY on PTC 4.

1 1964 (R1991) Steam Generating Units Background: Our company has recently started preliminary work for installation of a new coal pulverized burners on one of our generating units. The unit is rated at 165 MW, is pulverized coal fired, pressurized (FD fans only), includes economizer and regenerative air heaters, and has no recirculating air or gas fans or paths. The agreed-to criteria for testing the burners is PTC 4.1-1964. Both a baseline and post-retrofit test will be performed to evaluate the burners. The guarantee for post retrofit efficiency is based upon baseline efficiency. Question 1: On the Summary sheet, PTC 4.1-a, page 16, line 70 [Unmeasured Losses], should the percent used for unmeasured losses be the same for both baseline and post-retrofit testing or should the number used for baseline testing be 0.5% higher than that used for post-retrofit testing? The third footnote on page 17, form PTC 4.1-b, reads Unmeasured losses listed in PTC 4.1 but not tabulated above may be provided for by assigning a mutually agreed upon value for Item 70. Also note that Fig. 2, Heat Balance of Steam Generator, page 15, lists all the losses covered in PTC 4.1. It is recommended that the losses in Item 70 be estimated individually rather than as a group. Mutual agreement on the individual losses for the baseline and post-retrofit tests should be made. The code does not require that the estimates of the individual losses for the two tests be the same nor that they differ. The parties to the test should consider measuring some of the Item 70 losses if there is a probability that the type of burner affects the loss. Para. 1.07 allows for abbreviated tests in some cases, such as for routine testing. You proposed tests do not appear to be routine tests. However, if abbreviated tests are to be used, the test procedures for obtaining the major items shall be the same as specified in the Code. A change in burner design may affect temperatures within the furnace and furnace-gas-flow patterns. This may affect the distribution of ash quantities at the various collection points. Often, the distribution is mutually agreed, see para. 3.01.14. The parties to the test should exercise engineering judgment to determine if there is merit to measuring the ash quantities at one, or, more points.

Answer 1:

It is assumed that the baseline and post-retrofit efficiencies will be corrected for standard conditions before comparing. There is one correction that is not used in abbreviated tests that might be significant: the correction to entering air credit for changes in entering-air temperature. If the ambient air temperature at the time of baseline test differs significantly from that at the post-retrofit test, the differences in efficiencies would be affected. Question 2: On the Summary sheet, PTC 4.1-a, page 16, line 13, [Gas Temperature Leaving (Boiler) (Economizer) (Air Heater)], is it acceptable to take the reading at the economizer outlet (line 14, Fig. 1, Steam Generating Unit Diagram), or must the reading be taken at the air heater outlet (line 15, Fig. 1)? [Note that both baseline and post-retrofit testing will take place at the same point. Our goal is to test the burners without the changes in thermal efficiency of the air heaters affecting the tests.] The main body of PTC 4.1 identifies the test boundary at the Air Heater outlet when the unit includes an Air Heater.

Answer 2:

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