2.8.22 Dry Fly Ash Storage Silos

2.8.22               Dry Fly Ash Storage Silos

 

                        2 Nos. storage silos each to store 1000m3 of dry fly ash with adequate margins shall be provided. Storage silos shall be of flat/conical bottom type with the provision of air slides/fluidising pads at the bottom. Storage silos shall be provided to store precipitator fly ash with adequate air space.  This silo shall be used to collect dry fly ash for the purpose of sale. It shall have facilities for dry ash unloading into cov­ered road tankers and conditioned fly ash in open road tankers. The silos shall be R.C.C. constructed.

    

                        Each dry fly ash storage silo shall be provided with following arrangement for unloading the fly ash.

 

                        (a)        A retractable chute alongwith rotary feeder for unload­ing  the dry fly ash into closed road tankers at a rate of 120 T/hr. max.

 

                        (b)        A ash dust conditioner alongwith feeder for load­ing the conditioned ash into open road tankers at a rate of 40-120 T/hr.  The water content in the conditioned ash shall vary between 0 – 15 %

 

                        (c)        Two blanked connections along with isolation valves shall also be provided in the silo for future installa­tion of pneumatic equipment for transportation of a dry ash to third party and for installation of equipment to slurrify the dry ash to dispose off it through ash disposal system.

 

                        The storage silo shall be designed to provide a clear access of 5.5m for a road tanker to come under the silo and receive the ash from the retractable chutes. To facilitate locating these chutes over the road tanker opening, it shall be possible to move the chute in all directions in the horizontal plane. It may be noted that unloading system from Silo shall be suitable for both rail wagon unloading and closed tanker/open truck unloading.

 

                        Each retractable chute shall include a shut off device at the chute outlet, a level probe to determine the level of ash within the road tanker, dedusting and vent air systems, and a motor operated winch system to lower/raise the chute.

 

                        Each storage silo shall be provided with a separate and dedicated floor aeration system.  This aeration should only be required during silo unloading and should not be in operation during storage periods.

 

                        The silo aeration system shall be supplied by con­stant volume blowers. Any manifolds employed for air distribution in the aeration system shall be fitted with blank flanges at the mani­fold ends, to facilitate maintenance requirements.

 

                        A suitable dust suppression system at various levels of the silo shall be provided, if required.

 

                        The pressure/vacuum relief valves in the storage silos shall be provided.

 

                        Bag filters shall be provided on the storage silos for cleaning the aeration and displaced air before venting out.  The Bidders should provide exhaust fans to assist venting. Bag filters and fans shall be installed under cover, and the protected from all potential adverse weather conditions.

 

                        The dust loading from the outlet of the bag filters shall not exceed 50 mg/Nm³ under any operating condi­tion with 10 per cent bags plugged.  Bidders shall justify the selected air to cloth ratio of the bag filters.  The Bidders shall also supply details on how the air flow into and out of, the storage silos is balanced during different operating conditions. 

 

                        The provision of a proven dust collection system in the storage silos that separate out bulk of the ash from the conveying air shall be provided before the air is extracted through the bag filters.

 

2.8.22.1            Instruments

 

                        Each silo shall be provided with following instruments as a minimum :

 

                        a)         Silo ash level switches (High and Low)                            :           1 No.

 

                        b)         Level switch with the telescopic chutes

                                    (meant for unloading into closed tankers)                         :           1 No.

 

                        c)         Differential pressure gauge across the bag filter                 :           1 No.

 

                        d)         Differential pressure switch across the bag filter                :           1 No.

 

                        e)         Pressure gauge at the inlet of the bag filter                       :           1 No.

 

                        f)          Differential pressure gauge across the vent filter               :           1 No.

 

                        g)         Differential pressure switch across the vent filter              :           1 No.

 

                        h)         Pressure gauge at the inlet of the vent filter.                     :           1 No.

 

                        The bidder shall include any other instrument required to make the system safe, efficient and reliable.

 

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