typical pome proposal - may 2011

8/13/2019 Typical POME Proposal - May 2011

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PROPOSALFOR A

BIOGAS PLANT

FOR A

45 TONNES/HOUR FFB PALM OIL MILL

This document is the property of GLOBAL WATER ENGINEERING (GWE) Ltd.,Hong Kong. It shall not be copied, reproduced, transmitted or communicated to thirdparties without the explicit agreement of GWE.International Conventions of Berne (1886) - Paris (1896) Berlin (1908) Berne (1914)Rome (1928) Brussels (1948).

Rev. - - PROJ. No. -


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TABLE OF CONTENTS

1. COMPOSITION OF THE WASTEWATER .................................................................................................................. 12. PROCESS DESCRIPTION .............................................................................................................................................. 2

2.1 ANAEROBIC WASTEWATER TREATMENT (PROCESS FLOW DIAGRAM D101P-A+D101P-B) .............................................. 23. BASIC DESIGN DATA .................................................................................................................................................... 6

3.1 EQUALIZATION/COOLING OF THE WASTEWATER.............................................................................................................. 63.2 MIXING TANK (B105) ..................................................................................................................................................... 63.3 METHANE FERMENTATION (D101) .................................................................................................................................. 63.4 DBFTANK (S103)+SATURATOR (I102)+SLUDGE COLLECTION TANK (B106) .................................................................. 73.5 CONSUMPTION OF CHEMICALS........................................................................................................................................ 73.6 BIOGAS REUSE........................................................................................................................................................... 8

4. SHORT TECHNICAL DESCRIPTION .......................................................................................................................... 94.1 MECHANICAL EQUIPMENT.............................................................................................................................................. 9

4.1.1 Anaerobic treatment (Process Flow Diagram D101P-A + D101P-B) ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ... 94.2 PIPING.......................................................................................................................................................................... 164.3 INSTRUMENTATION-AUTOMATION-ELECTRICAL............................................................................................................. 16

4.3.1 Wastewater treatment (Process Flow Diagram D101P-A + D101P-B) ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... .... 165. DRAWINGS ................................................................................................................................................................... 19


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- PROJECT No: - SHT- BY : - 1

REV DATE DESCRIPTION BY CHK

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1. COMPOSITION OF THE WASTEWATER

=================================

The design waste production quantity, as well as all influent composition values are based on the

specifications from the client and on our past experience with a large number of palm oil mills.

From these data following design figures are obtained:

Factory capacity : 750 Tons FFB/day = 45 Tons FFB/h, 16.7 h/day

Specific wastewater production : 80 % of FFB

Design flow rate : m3/d 800

m3/h 25.0 (24 h/d, after equalization)

COD : mg/l 55,000

COD : kg/d 33,000

COD : kg/ton FFB 44.0BOD5 : mg/l 27,500

BOD5/COD ratio : 0.50

TS : mg/l 43,600

TSS : mg/l 19,000

pH : --- 45

Temp. : C 7080


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2. PROCESS DESCRIPTION

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2.1 Anaerobic Wastewater Treatment (Process Flow Diagram D101P-A + D101P-B)

The POME from the factory flows by gravity into an equalization pond (B101, out of

GWE scope). From the pond the POME is pumped (by means of P111A/B) into a mixing

tank (B105) where the pH adjustment is done with caustic soda (F101, P103). This pH

adjustment is particularly important in the initial start-up period (first 2-3 months). After

that, the caustic soda requirement will drop and may even become zero (stand-by only).

The mixing tank is covered and mixed with a top entry mixer (A105). The influent is

pumped (P101A/B) from the mixing tank into the digester (methane reactor D101).

Under certain circumstances (start-up, restart after outage, ) it might be necessary to heat

the wastewater in order to obtain and keep thermophilic conditions in the methane reactor.

For this purpose we have included a hot water boiler (H102). Hot water produced in the

boiler H102 is pumped (P113) over a spiral heat exchanger (E101) to heat the wastewater tothe desired temperature (about 55C). The boiler operates normally on LPG or propane but

it is also possible to use biogas. The biogas can be fed to the hot water boiler H102 bymeans of a biogas blower (C101), preceded by a demister (S102).


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For this type of wastewater, sludge with poor flocculating and settling characteristics (nogranulated sludge), is expected. This is mainly caused by the high TSS, high COD, high

protein and high inorganic salt content of the wastewater. For this reason, GWE selectedthe FLOTAMET-M processwhich consists of a methane reactor (D101) followed by a

sludge flotation stage (S103).

In the methane reactor the actual anaerobic fermentation takes place. Dissolved and

suspended organic matter are largely degraded by anaerobic bacteria (sludge), and

converted into biogas, a mixture of methane and carbon dioxide. Only little sludge growth

takes place during this process.

The methane reactor is of the ANAMIX-T or CSTR type. In the methane reactor(D101), the wastewater enters at the bottom and rises through an expanded bed of

anaerobic active methanogenic sludge. Good mixing by means of a top entry agitator(A103) ensures that the influent is in constant contact with the biomass.


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The effluent of the methane reactor flows to a special Dissolved Biogas Flotation cell,

called DBF-tank (S103). In this DBF tank, the anaerobic sludge flocs escaping the

anaerobic reactors are separated from the treated wastewater by flotation and recycled.

The principle of the Dissolved Biogas Flotation is similar to the Dissolved Air Flotation,

but using biogas instead of air.

In the DBF-tank, the solids are forced to float by fine biogas bubbles attaching to thesolids. The fine biogas bubbles are created by recycling clean effluent (P123A/B), in which

biogas is dissolved under pressure. This happens in the saturator (I102) where biogas is

dissolved under pressure (about 5 bar) by means of the biogas compressors C104A/B.After injection of the recycle flow in the DBF tanks, the sudden pressure release results in

the formation of fine biogas bubbles, which float to the surface, dragging the sludge flocs

with them.

The separated foamy sludge flows out of theDBF tank through a conical section at the

top, and is collected in a sludge tank (B106), from where it is returned (P106A/B) to the

mixing tank. Addition of a flocculation agent (polyelectrolyte) is foreseen (M101 +

P122A/B) in a pipe flocculator (A107) in front of the DBF-tanks, to increase the flotation

efficiency and improve the effluent quality as needed. Excess sludge can also be withdrawn

from this sludge tank B106.

The clarified outlet of the DBF tank is discharged or sent to the existing lagoons (out of

GWE scope).


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For safety and start-up reasons a flare (H101) is foreseen.

Elevated flare Groundflare

In basis, an elevated type of flare (H101) is foreseen. This type of flare is the cheapest type

of flare, but is not CDM compliant. However, since the biogas is used for electricitygeneration, under normal circumstances no excess biogas is to be flared off. The flare is

mainly needed for start-up and emergency use.In option, an additional price is given for a temperature controlled ground flare, which is

100 % CDM compliant.


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3. BASIC DESIGN DATA

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3.1 Equalization/Cooling of the Wastewater

- This is done in an equalization basin (B101, out of GWE scope)

- wastewater flow : 600 m/d, design value

- required hydraulic retention time for equalization and cooling: 1 day minimum

- corresponding active basin value: 600 m3

minimum

- influent temperature: 80C max.

- temperature after equalization: 55 - 65C

3.2 Mixing tank (B105)

- incoming flow from the equalization pond: 600 m/d = 25 m/h

- recycle flow from anaerobic treatment : 100 % or 25 m/h (of which part from thesludge tank B106 and the rest from the methane reactor D101).

- total incoming flow: 50 m/h

- required residence time: 1 h

- corresponding volume: 50 m

3.3 Methane Fermentation (D101)

- wastewater flow : 600 m/d. design value, or 33.3 m/h, design value (after

equalization), 24 h/day

- COD influent: 55,000 mg/l; 33,000 kg/d

- BOD5influent: 27,500 mg/l; 16,500 kg/d

- design hydraulic retention time: 10 days

- corresponding methane reactor (D101) water volume: 6,000 m3

- corresponding volumetric loading rate: 5.5 kg COD/m.d

- number of reactors: 1

- dimensions of the reactor:. liquid height: 11.5 m

. total cylindrical height: 12.0 m

. cross section : 522 m, diameter: 25.8 m minimum- COD total effluent: 8,250 mg/l

- BOD5total effluent: 2,2002,750 mg/l

- TSS effluent: 3,000 mg/1

- COD total reduction: 85 %

- BOD5 total reduction: 90 - 92 %

- Biogas production: 16,362 Nm biogas/d or 9,817 Nm CH4/d at 60 % CH4


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3.4 DBF tank (S103) + saturator (I102) + sludge collection tank (B106)

- Wastewater flow rate from factory: 25 m/h max- Sludge recycle from sludge tank (B106) to the anaerobic treatment: 50 %, which is 12.5

m/h

- Net flow rate to the DBF tanks: 25 + 12.5 = 37.5 m/h

- Max acceptable surface loading rate for the DBF tank: 6.0 m/m.h

- Required flotation surface: 6.25 m minimum

- 1 DBF tank of 3.2 m diameter

- Corresponding available flotation surface: 8.04 m

- HRT in sludge collection tank (B106): 20 minutes

- Corresponding volume of B106: 4.2 m

- Saturation recycle: 100 % of total incoming flow, 37.5 m/h

- HRT in saturator (I102): 3 minutes

- Corresponding volume of I102: 1.9 m minimum

- TSS load to saturator: 37.5 m/h x 15 kg TSS/m = 563 kg TSS/h

- Required biogas/TSS ratio: 0.05 kg biogas/kg TSS- Corresponding required biogas: 28 kg/h or 23 Nm/h (density biogas at 60 % CH4 is

1.214 kg/Nm)

3.5 Consumption of Chemicals

Caustic soda (NaOH)

Especially during start-up, some caustic soda will be necessary to control the pH of the

methane reactor. After start-up, this caustic soda dosage will eventually decrease, and will

most probably become zero (stand-by only).

- the maximum required amount of caustic soda is around 27.5 meq/l, or 1.1 kg pure

NaOH/mraw wastewater

- corresponding maximum caustic soda dosage: 600 m/day x 1.1 = 660 kg/day, or 1,320

kg/day of a 50 % NaOH solution

- at a density of 1.54, this means 857 l/day (36 /l/h)

NaOH will only be needed at start-up, and in exceptional circumstances (calamities, upsets,

overload, )

The projected NaOH consumption in normal operation is expected to be zero, based on the

following arguments:

High TKN-content of the wastewater, which results in a high buffering capacity ofthe wastewater.


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Thermophilic operation of the methane reactor (more CO2 is stripped from thewastewater to the biogas than in mesophilic operation).

Our process design including a large effluent recycle + a mixing tank (B105). Bothmeasures contribute to a reduction of the NaOH consumption.

3.6 Biogas reuse

1 Nm3/day biogas at 60 % CH4has a calorific value of 5,142 kcal, so total expected biogas

production is equivalent with 3,505,000 kcal/h (thermic). This is equivalent with 4,076 kW

(thermic) or 1,549 kWe (at 38 % net conversion efficiency).

Part of the biogas can be reused to heat the wastewater if required.

Maximum required heat capacity:25 m/h x (55-35)C x 1,000 kcal/m.C = 500,000 kcal/h

Corresponding amount of biogas required: 97 Nm/h, or 14 % of the available biogas.

If no biogas is available, LPG or propane is to be used.

Note that these are calculated values based on the design COD input and expected removalefficiency figures. Actual figures will vary with the quantity and composition of the factory

effluent


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4. SHORT TECHNICAL DESCRIPTION

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4.1 Mechanical Equipment

4.1.1 Anaerobic treatment (Process F low Diagram D101P-A + D101P-B)

A103 : slow running vertical agitator, 22 kW, all wetted parts in stainless steel

A105 : mixing tank agitator, top entry mixer in stainless steel, 2.2 kW, withmounting/lifting accessories

A107 : In line pipe flocculator, capacity 40 m/h.


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B101 : equalization basin, 600 m net volume minimum (OUT OF GWESCOPE)

B105 : mixing tank, concrete, 50.6 m volume, internal length x width = 4.5 m x

4.5 m, water height : 2.5 m, total height : 3.0 m

B106 : Sludge tank, closed with conical roof, 40 mbar pressure, 4.2 m net

volume, approx. dimensions: diameter 1.5 m, cylindrical height 2.8 m,

active height 2.4 m

C101 : Biogas blower, capacity 100 Nm/h at 150 mbar, centrifugal type, wetted

parts in cast aluminum and stainless steel, 3 kW.

C104A/B : Biogas compressors (1 stand by), 25 Nm/h at 5 bar, 5 kW


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D101 : methane reactor (ANAMIX-T)- vertical cylindrical concrete tank with a conical or dome roof (design

under roof pressure: 500 mm W.G.) diameter: 25.8 m; cylindrical height:12.0 m

- internal piping in HDPE

- coating : (coaltar) epoxy coating inside in the gas phase

E101 : spiral heat exchanger, in AISI 316, 500,000 kcal/h, capacity, to heat the influent

F101 : caustic soda storage tank, carbon steel or HDPE, content 30 m


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H101: BASIS Biogas safety flare, 900 Nm3/h capacity, elevated type, instainless steel, fully automatic operation

H101: OPTIONALBiogas flare, 900 Nm/h capacity, temperature controlled,

groundflare, in stainless steel, fully automatic operation


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H102 : Hot water boiler, biogas fired water heater, convertible to natural gas(start-up period), capacity 581 kW (500,000 kcal/h), safety control:

control panel, safety valve, temperature switches and temperaturetransmitters, O2trim control, VSD on combustion air blower

I102 : Saturator for the DBF tanks, capacity: 37.5 m/h, active volume: 1.9 m,

stainless steel, operating pressure: 5 bar

M101 : Automatic polymer operation unit, capacity 1.7 kg PE/h, material SS

AISI 304, accessories 3 mixers = one in each of the 3 compartments, 1

powder screw feeder with hopper


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P101 A/B : methane reactor feed pumps (1 stand by), horizontal centrifugal pumps,50 m/h at 20 m W.C., 5.5 kW

P103 A/B : caustic soda metering pump (1 stand by), 0 - 160 l/h automatically

adjustable (frequency control), 0.55 kW

P106 A/B : Anaerobic sludge pumps (1 stand by), positive displacement mono

pump, 15 m/h, automatically adjustable (frequency control), 3 kW.

P111A/B : influent pumps, excenter screw pumps (mono), 30 m/h, 5.5 kW

automatically adjustable by variable speed drive.

P113 : Hot water recycle pump, 50 m/h at 12 mWC, 4 kW, horizontal

centrifugal pump

P122A/B : Polymer dosing pumps (1 stand by), mono pump with integrated

frequency converter, capacity 2 m/h, 0.75 kW

P123A/B : Saturation recycle pumps (1 stand by), 40 m/h at 5 bar, 11 kW


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S102 : Biogas demister, for 100 Nm/h biogas, cylindrical tank in stainless steelwith built-in demister pad.

S103 : DBF-tank (Dissolved Biogas Flotation cell) package unit.Compact sludge separator with conical roof, sludge outlet section, inlet

diffuser, concave bottom with 4 clarified effluent outlet points, 4 samplepoints, access ladder.

Cylindrical coated carbon steel tank, with legs.Overall dimensions:

- total height = 8.0 m- internal diameter = 3.2 m


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4.2 Piping

wastewater HDPE + stainless steel AISI 304 around equipment

biogas stainless steel AISI 304

chemicals carbon steel or HDPE

process water carbon steel or HDPE

Piping supports in painted or galvanized carbon steel

Valve materials in accordance with piping materials

4.3 Instrumentation-Automation-Electrical

Complete set of instruments for safety and largely automatic operation

Preliminary list (can be changed during detailed engineering)

Instruments included in packaged units (flare, dosing pumps, BIO-SULFURIX) not

included.

4.3.1 Wastewater treatment (Process F low Diagram D101P-A + D101P-B)

Level 1 level probe/transmitter ultrasone type (LE/LT108) F

2 level probe/transmitters hydrostatic type (LT105, LT106) F2 level control valves (LCV105, LCV109) F

1 level probe/transmitter (differential pressure) (LE/LT110) F

Flow 6 electro-magnetic flow meters (FE/FT100, FE/FT101, FE/FT102,

FE/FT109, FE/FT110, FE/FT111) F

3 flow control valves (FCV101, FCV102, FCV110) F

2 biogas flow meters (mass flow type) (FE/FT103, FE/FT105) F

Pressure 2 pressure transmitters (PT102, PT103) F

8 pressure gauges F

1 pressure control valve (PCV102) F

Temperature 2 temperature probes/transmitters (TE/TT101, TE/TT102) F1 temperature control valve (TCV101) F

Analysis 2 pH probes + electrodes + cables (pHI101, pHI102) F

2 pH transmitters (pHT101, pHE102) F

1 online CH4meter (AT101) F

Control 8 frequency controllers (SC100, SC103, SC106A/B,

SC111A/B, SC122A/B) P


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Safety & 1 breather valve (SB101) FMiscellaneous 1 flame arrestor (SF101) F

Breather valve/Flame arrestor

Low tension/control panel

Central low tension/control panel. All equipment is operated from the SCADA computer

(see below). However, the panel is equipped with AOM switches allowing manual

operation of the motors for maintenance or in case the PLC/Scada system is down.


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PLC/Scada System Specification

The Plant has a PLC, brand Allen Bradley model COMPACT LOGIX. All logic and timingis done by this PLC.

All indications and alarms, as well as reporting on the daily operation of the plant, and

trending will be done by a Scada computer system. All motor start/st op as well as

auto/manual functions are also done from the Scada computer. The SCADA software used

is SPECVIEW.

A simplified flow sheet will be displayed on the Scada computers colour screen, featuring

all measurements (continuously updated) and indication of operating motors. Alarms will

be indicated by a colour change to red of the corresponding measurement or indication. An

external acoustic alarm is also foreseen.

The measurement values are stored on the PC's hard disk, and are used as computation

values for a daily plant operation report, printed by the PC's printer. There is a possibility

to introduce external (off-line) data from laboratory analysis (COD, ) in order to make

the plant operation report complete. In absence of such external data input, the computer

will use the design values as default values.


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5. DRAWINGS

==========

Attached following drawings:

- Flow diagram: Giving all equipment, main process lines and all instrumentation except

pressure gauges (PI) and temperature gauges (TI).

D101(A+B): Anaerobic treatment

typical pome proposal - may 2011

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