PVC Dryer Maintenance Procedures

8/11/2019 PVC Dryer Maintenance Procedures

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DOCUMENT :MC-9- PVC I / BaggingREV. NO. : 00

ISSUE NO. : 01

EFFECTIVE DATE : DEC 2013

PAGE NO. : PAGE 1OF 11

AREAS: ALL

Prepared By: ________________________________________

Reviewed By:

Ovais Anzar

___________________________________________Section Head / Unit Manager ( Maintenance )

Approved By: ___________________________________________NKQ (Maint Manager) /SAA ( Training Manager )

Change Record

. Rev. No. Page No. Section Description of Change

Distribution List1 LAN2 Training Manager (Original Copy)


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Purpose:

The purpose of the document is to provide an understanding on working, specificationsconstruction and repairs of PVC Dryer DR-1501at PVC I plant.

Abbreviations:JQP Job Qualification ProgramQSP Quality Standard ProcedureSOP Standard Operating ProcedureT/A Trade ApprenticeTAE Trainee Assistant Engineer

UM Unit ManagerTM Training ManagerVP Manu. Vice President Manufacturing


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1. Technical Specifications

Vendor: Comessa

REQ PXFF001

2. Equipment Parameters

PARAMETER VALUE

FEED PRODUCT

Wet Poly-Vinyl Chloride

CakeFEED RATE 14400 kg/hr

INLET MOISTURE 22%

OUTLET MOISTURE 0.20%

INLET TEMPERATURE 50-90'C

OUTLET TEMPERATURE 50-70'C

FLUIDIZATION AREA 41m2

HEAT EXCHANGERS Area (520 m2) Qty: 6


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3. WORKING PRINCIPLE OF DRYER (DR-1501)

The Dryer is designed for drying wet Poly-Vinyl Chloride Cake. The product comes fromtwo centrifuges by Screw Conveyor PM1501. The wet PVC is dispersed in the the firstsection of the dryer by Dryer Distributor PM1503.

Dryer DR-1501 is divided into two sections. In the first one the product is dried down to0.5% (wet basis) moisture. The first phase corresponds to free moisture evaporation. Asenergy carried by fluiding gases is low (low fluidizing velocity), drying is achieved bymeans of heat exchangers into the fluid beds. These exchangers are divided in 6independent items. They are heated by hot water. The second section of the dryer isintended to reduce moisture down to 0.2%. As releasing of water from 0.5% to 0.2% ismore related to diffusion rather than heat transfer, this section is not equipped with heatexchangers.

At the end of drying, product temperature is around 50-70%. The two sections of thedryer are separated by one partition. Product flows through the partition by overflow.However a trap door is provided at the bottom of each partition in order to completelyempty the fluid bed. Product is extracted from the dryer by Dryer Rotary Valve PM1505.

Hot Air for Drying is provided by two assemblies. Each is provided with a blower (BL1501& BL1502) and an air heater (HE1505 & HE1506). Dryer Air Filter FL1501 is common tothese two assemblies.

Exhaust Gas is extracted from the dryer by Dryer Exhaust BL1503. Dedusting of this airis achieved in a high efficiency cyclone (SR1501) and Scrubber SR1502, which is aventuri scrubber combined with a cyclonic column. Dusts are collected under the cycloneby Rotary Valve PM1504, and reintroduced in the dryer with a pneumatic diverter.

The design is made taking into account in air at 29.5C and 83% relative humidity. Inorder to avoid condensation it is necessary to inject hot air in the hood, in order todecrease the exhaust air humidity.

Detailed P&ID are in the next page.


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PM-1501

DR-1501

HE-1505

HE-1506

BL-1501

BL-1502

SR-1501

SR-1502


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4. CONSTRUCTION OF DRYER4.1 WINDBOX

One wind-box for air distribution under the plate. This casing is divided into two sections.The first section is divided in three parts. Each part is provided with an air inlet nozzleinspection door and a drain.Material: AISI 316-L Stainless Steel. The wind-box is reinforced by angle irons in StainlessSteel. Support lugs are provided.

HOOD

FLUIDIZATION BED

WIND-BOX


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4.2FLUIDIZATION PLATE

Air is distributed all over the fluid bed area by a Conidur type plate built in AISI 316 Stainless Steel. Thickness is 1mm.The direction of the holes will be adapted in order to convey the product towards the outlet.Total plate dimensions are:

- Width: 3800mm- Length: 10800mm

This plate is in several elements. Each plate element is welded on a frame. The frames arebolted between the wind-box and the hood.Material: AISI 316 L Stainless Steel.

Below is the detailed diagram of fluidization plate


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4.3FLUIDIZATION BED

This part contains the fluid bed. It is divided in two sections.

In the first one, free moisture is released, and the second one is intended for diffusion ofinternal water. The two sections are separated by one partition.Product goes from one section to the other by overflow. A pneumatically actuated trap dooris provided at the bottom of each partition in order to empty easily the fluid bed. Theseactuators are on/off type. Air set is provided. In the first section of this through, 6 sets of heatexchangers are installed.In the second section, a set of baffles plates is installed. These baffles plates are in astaggered arrangement in order to increase the path of the product (height: 1200mm). agood residence time distribution is obtained by that device.Baffles are made of folded plates.The through is reinforced by angle iron in Stainless Steel.

DIMENSIONS OF THE FLUID BED

Total surface : 41m2

Surfacezone 1 : 35m2Surface zone 2 : 6m2Width : 800mmLength : 10800mm

4.4HOOD

Fluidizing gas and dust are collected by a hood which is located just above the fluidizationthrough. This hood is supplied with doors and sight glasses with wipers and lights. It is in

AISI 316 L Stainless Steel. As exhaust gases have a high moisture content, the hood istraced with hot water (Double Wall). Moreover, two air inlet nozzles are provided each in thefirst part of the hood and between the two sections, in order to inject hot air to decrease thehot air relative humidity and to increase its temperature.Surface quality: 2BGaskets are in white neoprene.


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4.5HEAT EXCHANGERS

Energy required for drying is released in the fluid bed by set of 6 identical heat exchangers(total surface: 520m2). Heat exchanger is fed by water heated up-to 90oC. each exchangeis constituted by 52 heating plates. A minimal distance of 100mm is provided between thfluidization plates and heat exchangers, in order not to disturb the fluidization.These heat exchangers are supported by wheels on transversal rails. They can be easilremoved out of the fluid bed. Removal of the heat exchanger is done on the side of the fluidbed.

All the plates of exchangers are connected by two headers: one water inlet and one wateoutlet. These headers, which are outside the fluid bed, will be connected to the watecirculating loop (not provided by Comessa).Water valves and common collectors are excluded.

Dimensions of plates of one exchanger set:

Height : 840mmWidth : 1000mmPlate thickness : 1.5mm

Material : Avesta 254 SMO

4.6 DISCHARGE CHUTE

Heat-Exchangers


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The hood is provided with a product discharge chute. This chute is supplied with aninspection door and a weir. Product is transported out of the fluid bed, by gravity discharge,by Dryer Rotary valve PM1505, in AISI 316 L Stainless Steel construction for parts incontact with product.

5. CLEANING OF DRYER (WATER-JETTING)

5.1 PROCEDURE

1. Follow LOTO procedure for BL-1501, BL-1502, and BL-1503 & PU-1313.

2. Obtain work permits downstream flange opening and insulation removal

a) Remove insulation from dryer heater air outlet duct

b) Open bolts of dryer heater air inlet and outlet duct flange for draining of water and

inspection.

3. Obtain work permits for upstream elbow removal

a) Remove (or rotate 90o) elbow located at upstream of dryer heater air inlet duct

4.Obtain vessel entry permit and permit for cleaning

a) Clean the dryer inlet duct and exchanger with nylon brush (if required)

b) After cleaning with brush, wash the exchanger tube and shell with water

c) After cleaning with water allow it to dry with compressed air

5.2 BOX-UP

1) Final inspection of complete equipment to be done by:

2) Sign box up certificate

3) Obtain box up permit

4) Install back upstream elbow and downstream flange and tighten all the bolts

5) Remove Yellow lock from BL-1501, BL-1502, BL-1503 & PU-1313

6) Perform housekeeping of the work area


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7) Exchange permit copy

5.3 COMPLETION OF JOB

1) Place the tools back to the place.

2) Do the housekeeping of area.

PVC Dryer Maintenance Procedures

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