Boiling Out in Steam Boiler

Boiling out in steam boiler must be performed correctly according to procedure. Before a new boiler is put in service, the internal surface of steam boiler section must be cleaned to remove oil, grease and protective coating.

Before perform boiling out in steam boiler, all pressure parts should be properly inspected for interferences along with the required hydrostatic test created, the piping of blowdown and chemical which are connected to steam drum must be checked to ensure that they're clear and free.

As a way to lessen the quantity of foreign matter which might be presented into the boiler via the pre-boiler process, the pre-boiler process must be water-flushed. It's adequate for drying out of any kind of refractory comprised in the setting.

Mechanically eliminate grease and oil whenever possible from drums and headers prior to boiling out. Examine just about all drum internal pertaining to tightness of bolted components. The following equipment must be available for excellent functioning:

• Forced draught fan
• Induced draught fan
• Condensate storage tanks
• Sampling equipment
• Control equipment
• Deaerator
• Water fill-up pump
• Boiler feed water pump
• Firing equipment

It's necessary that the operators on responsibility for the duration of the boiling out operation are well known with standard firing and performing procedures and safe practices.

Preparation to boiling out in steam boiler:

1. Thermometers must be connected on the steam drum and water drum to evaluate metal temperatures.
2. The non-permanent drum pressure gauge of about 15 kg/cm² full range must be mounted.
3. The gasket must not be utilized for the duration of boiling out for the steam drum and water drum manholes. The non-permanent gasket must be fitted.
4. All of steam boiler instrument leads which aren't utilized must be isolated for the duration of boiling out.
5. Procedures must be designed to dissolve chemical for boiling out.

The procedures of boiling out in steam boiler:

1. It's assumed that all tubes are already examined for obstructions and the needed hydrostatic tests are already created. Ensure that all debris are eliminated from the drum. After having the common safety measures to make certain that the boiler and location are cleared of personnel, close the boiler (with the exception the drum vent) and also close all access and inspection doors.
2. Get rid of a manhole on the steam drum and fill up the boiler till water shows up in the drum.
3. Dissolve the needed amount of chemicals for early demand. As an early demand for boiling out, 0.3 kilograms of H₂SO₃, 4 kilograms of Na₃PO₄.12H₂O, and 2 kilograms of NaOH are suggested for every 1000 kilograms of water presented by the boiler and water walls whenever filled up to the suggested working level. These chemicals must not to be put in with a solid straight into the drum. In dealing with the chemicals and the solution, good treatment must be used to prevent injury to skin, eyes and clothing.
4. Add the chemical solution by means of the steam drum manhole and close the manhole. Right after the chemical solution have been put in, increase a drum water level to the suggested working level.
5. Close all superheater vents and also drains with the exception the outlet header drain on the last step. This must be kept open for the duration of the whole boiling out time period. Keep the drum vents wide open.
6. Purge and clear the furnace to make sure removing of combustible gases. Once the furnace is purged, the light oil torches or burners are lighted in a style to deliver the heat as uniformly as doable. Firing equipment, settings, vent, drain, etc. must be run while in normal start-up.
7. Fire the boiler to take the pressure approximately 10 kg/cm²G in about 8 hours. Maintain this pressure for 4 hours to make sure circulation. Close up the drum vents while the drum pressure gets to 2 kg/cm²G. At the same time check out expansion of the unit wherever doable.
8. Observation of the temperature of the water drum must be created for an indicator of excellent circulation so as that all components of the unit can be carefully boiled out.
9. Soon after 4 hours shut down all burners, permit the boiler pressure to reduce. Right after the pressure has decreased apparently (about 4.5 kg/cm²G) the water level must be increased in order that the gauge glass is almost full.
10. Blow down the boiler employing bottom blowdown valves. Don't permit the level to move out of sight in the gauge glass. Recover the water level to normal right after the blowdown.
11. Do it again this cycle (from item 7 to item 10) 3 times in overall, increasing pressure progressively, setting up the water level concurrently, keeping the higher pressure for 4 hours, the cutting the fires and blowing down.
12. Solution samples must be provided regularly while in the boiling out time period. When the boiler water alkalinity and phosphate concentration have decreased to ½ of the initial values, extra boil out chemicals must be included to recover the initial concentrations.
13. The boil out must be carried on till the solution sample show that oils and siliceous materials are taken off. If samples of the alkaline solution present no rise of oil (and below 5 ppm) or siliceous materials, the burners must be shut off and unit must be cooled progressively. If the drum pressure falls to 2 kg/cm²G, the drum vents and superheater header drains must be opened wide. If the steam drum metal temperature drops under 90^o C, drain the boiler.

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Chemical Cleaning in Steam Boiler

Chemical cleaning in steam boiler is performed prior to a new boiler is put in service; the internal surface of the steam generating section should be cleaned to remove oil, grease and protective coatings. The overall chemical cleaning procedures in steam boiler contains of two steps as follow cold degreasing and passivation.

Preliminary to boiling out:

1. The intent of degreasing is to remove the oils, grease and the other hydrocarbon or preservation oils.
2. The intent of passivation is to get a final passive film on the waterside heating surface.

Preparation of chemical cleaning in steam boiler as follow:

1. All pressure parts must be carefully inspected for obstruction and the necessary hydrostatic test made. Steam drum blowdown line and chemical feed line should be checked to be certain that they are free and clear.
2. Mechanically remove as much oil and grease as possible from drums and headers before boiling out. Check all drums internal for tightness of bolted parts.
3. Prepare all recommended chemical ready on site.
4. Check the leaks of the temporary lines flanges and fitting by circulating the water using circulating pump.

The procedure of chemical cleaning in steam boiler as follow:

1. Make up the closed circuits system with de-mineralized or condensate water.
2. Reduce the water level to allow the total amount of chemical entering the system with no over flow (assume 1 kg chemical is approximately equal to 1 liters).
3. Add the cold degreasing chemical as recommended.
4. Do a multi sampling system to ensure that the solution has fully mixed.
5. Perform continuous circulation for 8 hours to get sufficient contact time and satisfactory grease removal.
6. The oils sign should appears in the solution and add the de-mineralized water to make the oils sign overflow from the closed system.
7. If the final solution pH less than 9.5, so adjust the pH using the Trisodium Phosphate.
8. If the oil signs on the water surface has disappeared, cold degreasing is considered completed.
9. Drain the solution in the boiler system, flush the boiler using condensate de-mineralized water until the pH less than 9.

Recommended water quality during perform chemical cleaning in steam boiler:

1. After degreasing is finished, drain the water solution inside the system.
2. Flush the system with de-mineralized water to ensure that the turbidity has been lower than 10 NTU and the iron concentration has less than 2 ppm.
3. Inject the passivation chemicals as recommended.
4. Adjust the pH with amine to get the pH range of 9.5 – 11
5. Circulate for 4 – 6 hours.
6. Passivation is complete.
7. The solution should be maintained in the system until the boiler is ready to be started. Do not allow the boiler is in empty condition for a long time.
8. Use trisodium phosphate to increase pH.

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Boiler Evaluation

Boiler evaluation should be performed to make sure steam boiler can run properly and long life time. There some evaluation associated with boiler. However, two of all variables for evaluation are important to be known are fuel consumption and efficiency.

Other boiler evaluation should be assessed is boiler specification plus order. It will be vital characteristics seeing that the lifetime of a steam boiler over 25 years. Correct order can help save quite a bit in investment, working expenses and also a fault could be regrettable.

Due to the fact a steam boiler is a custom made product, it expenses plenty of time and attempt intended for the boiler manufacturer to get ready a bid and an similar attempt by the purchaser for evaluation. The attempts could be preserved in case the specification is organized properly and the boiler evaluation is performed effectively. It's usual to suggest the buyers of the evaluation conditions during the time of bidding process thus the proposals obtained are receptive and customized for complying.

The charge of fuel plus the plan of desire rates control loading elements. Increased fuel and desire costs require higher efficiency which justifies the extra price through a quicker gain on investment. The following factors must be considered in boiler evaluation:

• The initial action is a watchful study of the plant necessity within all conditions of functioning, at full load and section load. A suitable list of specifications is needed and simply afterwards are rates for bids required.
• A ask for quotation should contain variables for evaluation and the equivalent loading aspects, to allow the buyers to know the working idea and reply in the almost all proper method.
• The specification should obviously express what variables should be fulfilled without fall short and what products may perhaps be custom-made.

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Performance Testing of Boiler

Performance testing of boiler and heat balance are last stages of its execution. The last action of performance testing of boiler is implemented by running over of power plant and also finalized economical funds by the user. The guarantee time period of steam boiler begins after that. Consequently, it truly is very crucial in which the performance testing methods are performed impartially to prevent costly legal combat. Therefore, performance testing of boiler should be done in accordance with Code ASME PTC 4 (American Society of Mechanical Engineers Performance Test Code) or DIN 1942 for German Code or BS 2885 for British Code.

Performance testing of boiler is ideally performed at a new steam boiler prior to the normal use and also dissects controls in. However this can be commonly impossible for several factors. Once of purchase it can be common to determine the actual time frame restriction prior to performance testing of boiler might be done and the way in which it might be executed. In small scale of power plant it can be feasible to in-take steam as long as complete testing.

Whether performance testing of boiler is important to be performed? In case it isn't obligatory according to contractual conditions, Performance testing is usually eliminated due to the fact that it need a lot of preparation works such as equipment, tools, manpower, materials and the others. In addition, it can be important in which the power plant be given to the provider to permit for setting of steam boiler approximately seven days. This results in a specific impairment of boiler accessibility, which in turn the power plant would possibly not manage to pay for. Furthermore, the power plant users can simply decide whether a steam boiler is reaching performance requirements. A performance testing of boiler is commonly needed exclusively if there may be a worry of decreased or limited performance.

Major performance (%) = net output / total input

It can be primary rating of performance when the output of steam could be calculated. The following formula can be taken by replacing input = loss + output;

Major performance (%) = 100 - (heat losses / fuel input)

Performance assessment acts 2 functions:

1. Popularity of a repaired or new steam boiler to verify no matter if the guaranteed performance continues to be supplied
2. A program rating in a working power plant to evaluate no matter if training correction is required

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Performance Assessment of Boiler

A procedure of performance assessment of boiler must be integrated in the system of power plant. In addition to checking performance of equipment and tool, the personnel who operate the power plant could assess the influences of the incorporated plant control method. A system of efficient performance assessment of boiler can present appropriate performance of equipment that, any time provided as required, provides safe, inexpensive and efficient operation of boiler. Utilizing preventive maintenance programs which identify bad performance increases plant productivity and also provide the life of boiler is longer. Actual-period assessment and checking of important operating information allows the personnel create prepared and appropriate decisions.

Actual performance assessment of boiler and power plant is remarkable to determine considered performance programs for the reason that the considered performance of boiler or power plant's equipment could be compared specifically while using predicted performance within same working conditions. Therefore, real changes in performance of power plant and boiler equipment are effortlessly observed. Performance assessment for each unit is carried out based on Code ASME PTC (American Society of Mechanical Engineers Power Test Code).

The conclusion of essential characteristics of performance assessment of boiler as follow:

-          Showing final results at boiler system

-          Dedication of predicted boiler performance

-          Actual performance calculations

The following are performance assessment that shows to assistance personnel read the information:

-          Degeneration of plant parts show

-          Controlled variables show

-          Total plant performance show

Every class of shows is developed intended for a certain class of personnel. Such as, plant operations is involved in total present comparative to past performance of boiler or plant although the operators are involved with supervising controlled variables, permitting the best economical operation.

Stats are utilized in the performance assessment data, providing a assurance period per performance indication. Not necessarily understanding the correctness of provided calculation could result in mistaken results and next faulty selections on improvements and maintenance of equipment. It is consequently important to give quantitative indicator of the precision final result.

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Hydrostatic Test in Steam Boiler

Hydrostatic test in steam boiler is one of non destructive examinations which should be performed for new steam boiler or steam boiler which has been repaired such as replace water wall, superheater, reheater, economizer and so on to. Hydrostatic test must be done to make sure that steam boiler is free from leakage before start up is performed. Before hydrostatic test is executed, inspection for all welds and installation of pressure parts should be done. Moreover inside and outside of steam boiler and pressure part shall be free from all dirt, scale, paint, debris, dirt, weld slag, rust, oil, spatter and all other foreign matter. 

Before perform hydrostatic test (hydrotest) in steam boiler, the following matter should be prepared as follow:

1. Non-destructive examination shall be verified to confirm acceptance as per Code and specification.
2. Dimensional inspection. 
3. Full visual inspection for all welds. 
4. Boiler pressure part installation is completed. 
5. No painting work on pressure part before hydrostatic test. 
6. Inside and outside of boiler and pressure part shall be free from all dirt, debris, weld slag and spatter, oil, rust, scale, paint and all other foreign matter. 
7. Prepare and check valve line-up. 
8. All gags shall be installed on safety valve. 
9. Vent and drain are to be provided for the system before commence of hydrostatic test. 
10. All temporary fitting, blind flange shall be suitable for the test procedure and should not have defect that may cause failure during hydrostatic test. 
11. Fill boiler with treated water and free from mineral or other suspended matter (Demineralized water).

Requirement of gauge and record during hydrostatic test in steam boiler (hydro test): 

1. A minimum of 2 (two) pressure gauge shall be used for pressure tests. One shall be a pressure temperature recorder with a range suitable for recording of the test pressure. The full scale of the other pressure gauge shall preferably 1½ to 4 times of test pressure. 
2. The test pump and the line to be tested shall be provided with the separate indicating test gauges. In case of testing between a high and low point of the module, gauges shall be placed one at the top and one at the bottom to measure the pressured drop. 
3. The pressure gauge shall be calibrated and still valid before used. Any gauges showing incorrect zero error more than + 1% of full-scale range shall not be used without repair and recalibrate. 

Hydrostatic test must follow the determined procedure which is generally as follows: 

1. Install suitable temporary fitting such as blind flange or end plate to close opening and ensure all of openings are closed except venting valve. 
2. Fill the steam boiler with treated water, free from mineral or other suspended matter at temperature not under 70 F or ambient temperature. 
3. Inspect leakage when steam boiler is being filled, remove air through venting valve, close it if there is not leakage and air is totally removed. 
4. Increase pressure gradually with maximum pressure rate 5 kg/cm2 until 1.5 times of maximum allowable working pressure for new boiler and 1.2 times for repaired boiler. 
5. Record pressure, time and temperature during test and inspect all of pressure parts of steam boiler at holding time of hydrostatic test approximately 10 minutes. 6. After hydrostatic test, the pressure should be release in a manner and at rate so as not to endanger personnel or damage equipment.

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