How to calculate the quantity of oxygen required for gas cutting operation?

 We know that, for gas cutting operation generally we use combination of oxygen and LPG or Oxygen and acetylene.But now a days for some industry LPG is banned for safety point of view.

 

Following table gives the difference between Oxy-acetyle and Oxy-LPG gas cutting

COMPARISON BETWEEN ACETYLENE AND LPG FUELS FOR GAS CUTTING OPERATION
SL No.	Acetylene	LPG (Propane)
1	Highest flame temperature up to 3100 Deg C	Flame temperature up to 2800 Deg C
2	Flame speed up to 7.5 m/sec	Flame speed up to 3.3 m/sec
3	Most of the heat released is in inner cone	Most of the heat released is in outer cone
4	Higher flame GCV of inner cone (4500 kcal/M3)	Lower flame GCV of inner cone (2500 kcal/M3) as compared to acetylene
5	Stoichiometric air fuel ratio1.2:1 (Requires 2.5 to 3 Oxygen cylinders for burning one Acetylene cylinder)	Stoichiometric  air fuel ratio 4.3:1 (Requires 7 to 8 Oxygen cylinders for burning one LPG cylinder)
6	Can be used in gas welding, as acetylene when burning with air creates reducing zone that cleans the steel surface	Cannot be used in gas welding as it does not create reducing zone
7	Acetylene has Specific gravity 0.9 kg/m3, so if it leaks it will raise in air without harming much	Propane  has Specific gravity 1.6 kg/m3,which is heavier than air.So if it leaks it will concentrate in deck level or any other closed/corner area
8	Acetylene requires less air for complete combustion	Propane requires more air for complete combustion, so there may be chances of formation of carbon monoxide (CO) in case of incomplete combustion. This incomplete combustion may result into poisoning of working area, as CO is poisonous gas
9	Can be used for cutting & welding applications in industry	Used only for domestic applications

 

Calculate the number of Oxygen cylinders required to consume 1 no.of industrial LPG cylinder for gas cutting operation

Commercial LPG (C3H8) has 19 kg weight that is 19 kg of propane

Combustion equation of propane

C3H8 + 5O2 = 3CO2 + 4 H2O

44 + 160 = 132 + 72 (Molecular weight of C = 12, O = 16, H = 1)

 Divide equation by 44

1 + 3.63 = 3 +1.63

 From above result it is clear that 3.63 kg of Oxygen is required to burn 1 kg of Propane to achieve 100% combustion.

So for burning 19 kg of commercial LPG, need 19 X 3.63 = 68.97 Kg of oxygen

 Volume of oxygen cylinder in cylinder = 6.9 M3 compressed at 140-150 kg/cm2

Convert 6.9 to kg by dividing oxygen density, we get weight of O2 in cylinder = 9.1 kg

 So total O2 cylinders required = 68.97 / 9.1 =7.58 Nos for consuming 1 LPG cylinder

Calculate the number of Oxygen cylinders required to consume 1 no.of dilute acetylene cylinder for gas cutting operation

DA (C2H2) cylinder has 8 m3 of acetylene

 Convert volume to kg by multiplying the density of the gas

8 X 0.899 = 7.192 kg

Combustion equation of propane

2C2H2 + 5O2 = 4CO2 + 2H2O

52 + 160 = 176 + 36 (Molecular weight of C = 12, O = 16, H = 1)

 Divide equation by 52

1 + 3.07 = 3.38 +0.69

So for burning 7.192 kg of DA, need 7.192 X 3.07 = 22.07 Kg of oxygen

So total O2 cylinders required = 22.07 / 9.1 =2.42 Nos

 Read Powerplant maintenance calculations

Note:

DA (Dilute Acetylene): OD 265 mm X Height 1 meter (Appx) and thickness 4.0 mm.Volume of acetylene in cylinder is 8.5 m3

 Oxygen cylinder size : OD 235 mm X Height 1.34 meter (Appx) and thickness 4.0 mm.Volume of O2 in cylinder is 6.9 m3

 

For more read>>>power plant and calculations

 

IBR STANDARD INSPECTION PROCEDURES

 

A-Standard Inspection procedure for Dry & thorough inspection

• Checking the registration number of the Boilers
• Carryout thorough inspection of Boiler from both inside and out side
• Check for defects like corrosion, erosion, bend, bulging, pitting, deformation, thermal expansion etc of pressure parts
• Check thickness of pressure parts
• Check the conditions of mountings & fittings
• Witness non destructive tests if required

B-Standard procedure for ground inspection of pressure parts under erection

• Verification of documents of pressure parts with relevant certificates
• Verification of approved drawings
• Checking pressure parts makers stamp & other identification marks with form no-II
• Checking of leading dimension of the parts & comparing with approved drawings
• Checking general condition of the pressure parts like dent marks, pitting, bend etc
• Checking of fittings & mountings with relevant drawings

C-Standard procedure for material inspection

• Verification of the approved drawings corresponding to the materials & documents
• Checking of the pressure parts materials with relevant IBR certificate and  approved drawing.Check name of the material, its specification, heat no, cast no.class, size, identification number & stamping etc
• Checking of leading dimension of the parts & comparing with approved drawings
• Checking general condition of the pressure parts like dent marks, pitting, bend etc
• Selection of samples for physical and chemical analysis/testing

D-Standard Procedure for weld set up inspection

• Verification of approved drawing
• Verification of Welder’s certificate
• Verification of the certificates of welding consumables
• Verification of the approval of contractor for particular job
• Verification for the procedure of welding procedure
• Verification for the site satisfactory  simulation test results
• Verification of test results of pipe, tube or plates
• Checking of root gap,weld groove profile and alignment of the pressure parts to be welded as per approved drawing
• Ensure weld joint area to be welded is free from dust, dirt, oil & grease.And also ensure it is crack free
• Check weld joint identification number.

E-Standard Procedure for welding joint inspection

• Visual inspection of general condition of the weld joint like, slag, under cut, finish, surface crack, leg length etc
• Check alignment of the pressure parts
• Witnessing Dye penetrant test, magnetic particle inspection test & hardness tests if required
• Selection of weld joints for NDT test like ultrasonic & radio graphic tests

Read Powerplant O&M reference books

F-Standard Procedure for Boiler Hydraulic tests

• Verification of the satisfactory non destructive tests of the welding joints
• Verification of PMI (Positive Material Identification) report of the weld joints
• Verification of pressure parts calculation approval
• Verification of all previous inspection reports and Post weld heat treatment (PWHT) charts
• Check the calibration reports of pressure gauges using for hydraulic test
• Witnessing Hydraulic test carried out as per IBR-1950
• Checking of deflection, distortion and extension of pressure parts during hydraulic test
• Thorough inspection of pressure parts for any leakages and sweating

G-Standard Procedure for Boiler steam tests

• Verification of the provisional order of the Boiler
• Witnessing the steam test carried out as per IBR-1950
• Check, popping pressure, reset pressure, blow down, accumulation, chattering, lift
• Checking of the performance of the mountings and fittings

 

Read more >>>> Power plant and calculations

 

Chain conveyor troubleshoot guide

 

Sl No.	Problems	Potential Cause	Solution
1	Chain rises off from sprocket	1. Excess chain slack.	1. Adjust the amount of slack equally at both sides.
		2. Excess wear at the bases of sprocket teeth.	2.Carryout hard facing of the sprockets
		3. Excess chain extension.	3. Replace the elongated chain parts.
		4. Foreign material stuck to the bases of sprocket teeth.	4. Remove the foreign material from the bases of the teeth.
		5.Reverse rotation of conveyor	5.Avoid reverse rotation of the conveyor when chain tightened is uneven
		6.Uneven chain tightening of chain
2	Chain separates poorly from the sprocket.	1. Sprocket misalignment.	1-Adjust alignment.
		2. Excess chain slack.	2-Adjust the amount of slack.
		3. Excess wear at the bases of sprocket teeth.	3-Avoid uneven tightening of the chain
		4.Uneven chain tightening of chain
3	Wear to sides of link plats and sprockets	1-Sprocket misalignment.	1-Adjust alignment.
		2-Trough width is lesser than required	2-Increase trough & runner flat width as per site conditions & links assembled width
		3-Chain runner flats size is less
4	Poor chain flexure	1-Inadequate oiling/lubrication	1-Lubricate properly, use standard lubricant during chain assy.
		2-Foreign materials between pins and bushes.	2-Wash the chain to remove foreign materials, and then oil it.
		3-Corrosion between bushes.	3-Replace with an environment resistant chain series.
5	Abnormal noise	1-Chain is too tight or too loose.	1-Adjust the chain slack.
		2-Inadequate oiling.	2-Lubricate properly.
		3-Excess wear of sprockets and chain.	3-Replace chain and sprockets or get worn-out area filled & hard face it
		4-Sprocket misalignment.	4-Eliminate contact with the case.
		5-Slats touching the trough
6	Chain vibration	1-Excess chain slack.	1-Adjust slack.
		2-Excess load vibration.	2-Reduce load variation
		3-Excess chain speed leading to pulsation.	3-Use guide stoppers to stop chain swaying.
		4-Chain flexes poorly at some points.	4-Replace the more worn-out chain parts during overall maintenance
		Sprocket wear.
		5-Worn out or more clearances in rollers & bushes
7	Damage to pins, bushes, rollers.	1-Inadequate oiling.	1-Lubricate properly.
		2-Jamed foreign bodies.	2-Remove foreign bodies.
	Deformation of link plate holes.	3-Corroded components.	3-Review chain and sprocket selections.
		4-Use with greater than allowable load.	4-Eliminate the abnormal load, and review chain and sprocket selections
		5-Abnormal load action.
8	Chain link cut or pins cut	1-Overload operation	1-Ensure all over load, ZSS protections are working
		2-Low breaking load of chain	2-Select chain with higher breaking load if this problem persists

Points to be kept in mind

1-Never weld the heat treated chains, as heat effect can reduce the strength & cause chain to break

2-Never go for electroplating of heat treated chain links, as it causes the hydrogen embrittlement failure

3-Do not use new chain on worn out sprockets

4-Gradual elongation of chain above 3%  in total chain length, indicates that the chain will soon jump the sprockets

Read SOP Coal handling & DE system