Fault Listing for DDCC S320 for SAACKE Burner user with DDCC BMS

This fault has occurred for one of the following reasons:

F1 – Gas incorrect position
A drive positioning fault has occurred, which will cause a safety shutdown of the burner.

F2 -Oil incorrect position
During close position prove, when a drive stops at a position which is outside the close set position by more than five degrees.

F7 – Sec.air damper incorrect position
During purge position prove, when a drive stops at a position which is outside the close set position by more than five degrees

F9 – Prim.air damper incorrect position
During pre purge, ignition or post purge, when a drive moves from its set point.

F10 – Recirc.air damper incorrect position
During modulation, when a drive is not at its correct set point as defined by the commissioned fuel/air ratio for the selected profile.

F8 Variable speed incorrect position
A drive is defined as having moved from its set point if its positional error is more than 1o for 15s, or more than 5o for 1s.

What causes Machinery Unbalance?

Unbalance occurs when the rotor’s mass is no longer at the center of rotation.  Unbalance can be caused by many factors:

• Assembly error
• Machine tolerances
• Eccentric components
• Wear
• Corrosion
• Thermal distortion
• Mechanical distortion
• Material buildup
• Bent components
• Broken components

Many things can prevent the successful correction of unbalance. Equipment resonance, bearing issues, product buildup and many more equipment problems can prevent a successful balancing  job from being completed.  All Equipment defects should be corrected before attempting to balance equipment.


Info from Ludeca

10 Ways to Select A Happy Pump

1)  Only select pumps with suction specific speeds less than 11,000-less than 9,000 is even better.

2)  Select your pump so it never operates below 70 percent to 80 percent of its best efficiency point.

3)  Remember that 1800-rpm pumps are usually more reliable than 3600-rpm pumps

4)  Hydraulic efficiency peaks at specific speeds between 2000 and 3000 and drops dramatically below a specific speed of 500. Higher efficiency means less vibration and noise and lower energy bills.

5) Use double suction impeller sparingly. They are less stable at off-design conditions than single suction impellers.

6)  For single stage pumps never select a pump with a maximum diameter impeller. You may need to increase the impeller diameter in the future.

7)  Select a driver that allows you to operate to the end of the pump curve.

8)  Use hydraulic stability, not temperature rise, as criteria for setting the minimum acceptable pump flow.

9)  Incorporate a healthy NPSH margin or ratio, i.e. NPSH _r/NPSH_a into your selection. This ratio should be anywhere from 1.1 to 2.0 depending on the fluid, criticality and suction energy level. A higher value is always better.

10)  Consider fluid volatility when making your pump selection. Be more conservative when the fluid has a single boiling point, as opposed to a fluid with a wide boiling point range.

Tips From Robert X. Perez

The Unwritten Laws of Engineering

Below is an excerpt from one article I read:

• However menial and trivial your early assignments may appear, give them your best efforts.
• There is always a premium upon the ability to get things done, and this requires energy, resourcefulness, and persistence.
• Before asking for approval of any major action, have a definite plan and program worked out to support it.
• Strive for conciseness and clarity in oral or written reports; be extremely careful of the accuracy of your statements.
• One of the first things you owe your supervisor is to keep him informed of all significant developments.
• Whenever your work affects another department or another employee, make sure they know what you are doing, and why.
• Get the facts, make an analysis, apply judgment, and make a decision; do not hesitate or be indecisive.
• Be interested in the people who work with you or for you, and treat them as you would want to be treated.
• Regard your personal integrity as one of your most important assets.
• Be careful of your personal appearance; if you are an executive, look the part.

However, the following summarizes the above information best:

 

“You should make an effort to learn what is expected of you in your job. Realize that people do form first impressions of you; people do appraise your appearance, the way you conduct yourself, and your ability to accomplish assigned tasks; and these evaluations are being made all the time.”

 

Have A Nice Day. Cheers.

 

 

The Brayton Cycle

The individual most commonly associated with the concept of the combustion (gas) turbine engine was an American named George Brayton (1830-1892).  He was an engineer with vision and ingenuity, who conceived the gas turbine thermodynamic cycle back in 1872, when he filed for a patent.  Discussions about gas turbines need to begin with Brayton.

Brayton conceived an engine that compressed atmospheric air to a high pressure.  In his concept turbine, the compressed air would then be mixed with a fuel (most commonly natural gas or #2 distillate oil) and ignited in one or more combustion chambers.  The excess air (that is, air not needed in the combustion process) would then be used to dilute and reduce the high-temperature combustion gases to a more moderate level, without significantly reducing the pressure leaving the combustors.  This would be known as combustion at constant pressure.

In Fig.1 below, air from the atmosphere adjacent to the turbine is drawn in and compressed, as shown from point 1 to point 2. Notice that the volume decreases as the pressure rises.  Heat is then added between points 2 and 3 on the graph.  However, the pressure remains essentially constant, as represented by the horizontal line on this pressure-volume (P-V) diagram.


Take a few minutes to study all aspects of the graph below.  Pressure is on the vertical axis (ordinate); Air Volume is on the horrizontal axis (abscissa).  Notice how volume decreases as pressure increases along the up slope from Point 1 to Point 2.  Trace the line from the Start Point 1 around to Point 4. Imagine how the pressure and volume change along the route.  Notice where heat is added to the compressed air.

Fig. 1-1 Pressure Volume Diagram for Brayton Cycle

Thereafter, the hot gases expand through stationary nozzle segments that direct the flow to impinge on the turbine blade surfaces (a.k.a. buckets) and develop torque (power).  According to Brayton, power will be developed by the gases applying impulse forces on the turbine rotor blades. Additional power results from reaction forces of the hot gases accelerating away from the turbine blades.  These TWO forces develop rotational power to turn turbine wheel(s).

An extension shaft from the turbine wheels would then be connected to an electric generator or other load device to do useful work.  Brayton envisioned that approximately 2/3 of the power developed by the gas turbine would be required to drive the turbine’s own axial-flow compressor and such required auxiliaries as fuel, oil, hydraulic and water pumps.  Finally, the exhaust gases would then be sent to a diffuser (to reduce the flow velocity) and out to the atmosphere through a stack enclosure.

The Brayton Cycle is considered to be an open system, since the exhaust gases are expelled back to the atmosphere from whence they originated.  Please refer to Fig. 2 below.

          Fig. 1-2 Gas Turbine and the Brayton Cycle

The stick diagram (Fig.1-2 above) and the associated pressure-volume diagram (Fig. 1) clearly show the gas turbine in its most rudimentary form.

The four numbered corner points show following modes:

• Points 1 to 2: Compression (air drawn from atmosphere and compressed)
• Points 2 to 3:  Combustion (combustion at essentially constant pressure)
• Points 3 to 4: Expansion (expansion across turbine section)
• Points 4 to 1: Exhaust (exhausting hot gases back to atmosphere)

The Brayton Cycle, in its simplest form, is not particularly complicated.  However, it took almost 60 years before working engines were developed.  This was due, in large part, to the fact that Brayton’s idea was one whose time had not yet come. Technology lagged behind his concepts because the need was not yet beckoning for such a device as a gas turbine.

The axial-flow compressor requires work to compress the air (W1-2) as shown in Figure 1-1.  Energy, in the form of fuel (natural gas or #2 distillate oil are the most popular), is injected into the combustor(s) shown as Q2-3. The output work developed between W3-3’ is required to power its own compressor and auxiliaries. The remaining power (W3’-4) is used to drive a load device (generator or load compressor).  The gases going to the atmosphere are hot, but this is often wasted energy (Q4-1), unless heat recovery equipment is employed.

Figure 1-3 below shows gas turbine operation for three different ambient conditions: an ISO day (compressor inlet temperature of 59 ˚F day, which is 15˚C) is represented by the sloped line in the middle.  To the left is the characteristic control line for a MAXIMUM ambient day (assume something like 100 ˚F at the compressor inlet).  The third line shows a loading curve for MINIMUM ambient day (assume 32 ˚F at the inlet).

Fig. 1-3 Base and Peak Load Operation for 3 Ambient Days

Loading the gas turbine from No Load to Rated Load for the ISO day, the fuel flow and exhaust temperature would track along the center line until the BASE load limit is reached.

• If PEAK load is then selected, the curve would track higher to intercept the upper line.
• On a MAXIMUM ambient day (hot), the governor control would track along the line on the left until BASE or PEAK load was intercepted, as desired.
• Similarly, a MINIMUM ambient day (cold) is reflected in the governor tracking along the right-side line to BASE or PEAK load.  Notice that a different BASE load level is achieved depending upon the ambient day of operation.  For instance, suppose the outside temperature at the compressor inlet is 32 ˚F, more power would be developed than on an ISO (59 ˚F) day.
• Much more power would be developed on a 32 ˚F day than on a MAXIMUM (say 100 ˚F) day, but fuel costs will increase too.

There are some minor efficiency gains on colder days, but for the most part this additional power is developed as a consequence of more fuel being burned in the combustors.  This raises the pressure acting on the turbine blades (buckets).  It costs the gas turbine operator more in fuel for the additional power generated.  However, the cost per kilowatt generated decreases.

George Brayton never lived to see his concept engine, the gas turbine, become a reality.  If he lived today, the F-class gas turbines that develop upwards of to 200 megawatts would likely bring a grin to his face some 14 decades later.

Taken From Blackstart

How Accurate Are Dial Indicators for Shaft Alignment?

Dial indicators are ubiquitous in shaft alignment; they have been used (and misused) extensively for alignment throughout industry for many years. In the right hands, a very accurate alignment can be performed with dial indicators. However, even under the best of circumstances, it will be a time-consuming task with many traps and pitfalls for the unwary or the untrained.


Using dial indicators properly for shaft alignment is almost an art form. One key consideration is the measurement setup. What method should be used? The Rim & Face Method? Rim & Reverse Face Method? Reverse Indicator Method? Rim & Two Face? The Face-Face Distance? Each setup may be appropriate for one situation but not for another. Extensive training is required to make this decision correctly. In addition, some proficiency with algebra and geometry will inevitably be required to make sense of the readings taken and calculate corrective moves for the machines.

Once the proper method has been chosen, initial setup preparations require the millwright to check for sag. Sag (also called bar sag) is the result of gravity acting on the overhung hardware spanning across the coupling that holds the indicator(s). It is always present, and its magnitude and repeatability must be accurately measured and known for the millwright to have any hope of measuring the misalignment accurately.

The effect of bar sag is doubled:
When initially zeroed at the top, this radial (rim) indicator is already sagging; when it is rotated 180 degrees, it now sags in the opposite direction, doubling the travel of the indicator.

Over longer spans (such as with spoolpiece couplings or jackshafts), sag can quickly become unmanageable, forcing the use of alternative compound setup methods. Sag will also affect a face (axial) indicator, but to a lesser extent. When bar sag is ignored, the impact on the readings can be very significant, rendering the data obtained misleading, or at worst useless.

Besides sag, field conditions may conspire to bedevil the results. Consider the following:

Vibration:

Surrounding running machines may cause vibration to enter the machines you are aligning, making the indicators vibrate as well. Because of the overhung installation of the indicator and its supporting hardware, this vibration tends to be greatly amplified at the indicator itself, to the point where it becomes difficult to read accurately, or even impossible to read at all.

Tilted Indicator:
Space constraints may force you to install the indicator at an angle to the reference surface being measured. This tilting will lead to a significant error in the readings as the movement being measured results in a significantly reduced travel of the indicator stem. The only way in which the travel of the indicator stem can accurately reflect the movement being observed is for it to be mounted perpendicular to the direction of the movement being measured.

Parallax Effect and Reading Error:
If space constraints do not allow you to view the face of your dial indicator squarely, you may misread the indicator by several thousandths of an inch. Also, if the travel of the indicator stem is not observed all the way around, a huge reading error may occur if the needle reversed direction during rotation and the millwright did not notice this. The consequences of such a mistake might be recording a reading as +40 mils when in fact it should be –60 mils! A similar error can occur when reading an indicator with a mirror in order to be able to see it at locations that are inaccessible to the naked eye, or from not noticing that the indicator stem is no longer contacting the reference surface.

Indicator Resolution:
Another concern is the measurement reso-lution of the dial indicator. If a delicate measurement task is undertaken, such as measuring the effect of machine frame distortion by observing the angular changes at the coupling, it must be remembered that these effects dwindle through mechanical looseness and the fact that the shaft is midway between the feet laterally; thus, when one machine foot is loosened, the effect on the shaft is halved. This, coupled with insufficient measurement resolution of the indicator may render the reading inadequate to perform meaningful diagnosis of the distortion condition.

Indicator Hysteresis:
Hysteresis of the indicator may also conspire to reduce the accuracy of your readings. Hysteresis is friction of the internal moving parts of the indicator mechanism. The best dial indicators use precious jewels in their movements (like fine watches) to keep them from “sticking”. This makes them delicate instruments that must be handled with great care. Dropping a dial indicator or subjecting it to extremes of heat, cold or humidity may exacerbate hysteresis conditions to the point that the indicator becomes inaccurate or inoperative.

End Float (axial play):
End float, or shaft end play, can bedevil a face indicator. This is particularly true on machines with journal bearings or sleeve bearings that permit a certain amount of axial play to occur in the shaft as it is rotated. This will play havoc with the accuracy of a face (or axially mounted) indicator. It can only be overcome by rotating the shafts while applying significant thrust load (which is often impracticable) or by means of the Rim & Two Face Method, whereby two face indicators are mounted on the same setup 180 degrees opposed from one another. When the shafts are turned, end float will affect both face indicators equally and therefore only the difference in their readings is observed, arriving thereby at the true gap difference between them. However, a great disadvantage of this method lies in the fact that an extra indicator is now required to be mounted, which in turn requires full rotational clearance all the way around; in addition, the extra indicator significantly increases the bar sag of the entire setup.

Obstructions to Rotation, Measurement Range, Algebra and Geometry:
The millwright using dial indicators must be proficient in geometry to understand the meaning of the readings he is obtaining; then, he must also be proficient in algebra to perform the necessary rise over run calculations needed to obtain the corrective moves for the alignment. One alternative is to a full rotation of the shafts when obstructions to rotation exist is to rotate the shafts only 180 degrees and extrapolate the fourth (or missing) reading through the mathematical circular validity rule. This requires some mathematical skills of the technician in the field. Moreover, the nature of misalignment is such that an elliptical math model is more accurate than a circular one; however, neither the resolution of the dial indicators nor the math skills of the technicians in the field is equal to the task of applying these models in the calculation of results.

When radial obstructions to rotation exist that do not allow for even a half rotation of the shafts, very few millwrights have the necessary mathematics skills to compute the misalignment conditions and corrections from shaft rotations of less than 180 degrees. Moreover, if misalignment causes the indicator stem to run out of range, it must be repositioned for fresh range, adding complexity to the calculations, since segments of readings must be “spliced” together. If an indicator bottoms out the entire reading process must be begun again, since the initial starting reference position of the indicator has been compromised.

All of this tells us that performing competent shaft alignment with dial indicators is a painstaking and time consuming task. As we have seen, there are numerous potential pitfalls and conditions that make extensive training and experience a necessity in achieving good results with dial indicators, and an unavoidable expense in downtime in getting the job “done right the first time.”

Taken from Ludeca Blog