DGA Co Ltd, Tel. No: 02 674 3077; E mail : dga@dga.co.th; www.dga.co.th

Main features of the DGA Eckrohr boiler are :- The boiler is manufactured under license from ERK Eckrohrkessel GmbH of Berlin

Germany, for many, the world’s premier boiler designer. The ERK license family have built in excess of 6000 boilers since ERK was formed

some 60 years ago. Most boilers are installed in Europe. The boiler is suited to both Biomass and RDF (Refuse Derived Fuel) combustion.

The 3 pass design is a very versatile design and suitable for all fuels. The Vee Grate was designed specifically for the ERK boiler, allowing the boiler to be

compact, and to use all the advantages of a staged combustion firing, ie highefficiency, low Nox and low CO with low excess air with a wide range of fuels see P3

ERK designed boilers can be factory assembled, and then ‘knocked down’ fortransport to site for final erection. This reduces expensive site time

The advantages listed on page 2 explain why the ERK boiler are so favored byboiler operators world wide

The boilers are generally built to ASME code and can be completed anywhere thefacilities exist to the meet this standard.

The Single Grate range extends from 10 tn/h to 60 tn/h boilers with high pressureand temperature, can generate from 1 to 12 MWe from a suitable turbine generator.

PRODUCT DESCRIPTION P 100.1

ECKROHR POWER BOILERS, SINGLE GRATE FIREDfor producing steam from SOLID FUEL

DGA ECKROHR BIOMASS BOILER WITH VEE GRATEThis boiler is rated for 45 tn/h steam at 65 barg pressure and 490 C

ADVANTAGES OF DGA ECKROHR BOILER

Quick Start Up– At start up water circulation starts very quickly as the distances from downcomers

to the heated risers on the water side are consistent and short– the short distances mean that all water tubes reach saturation temperature quickly,

so potentially dangerous thermal stresses in the boiler are avoided– There is no bottom drum containing large quantity of water which must be heated

during start up on bi-drum designs– The steam drums is isolated from flue gases so thermal stress and corrosion in this

area is avoided. Bidrum boilers are generally swept by the flue gases.– The tube connections to the drum on an Eckrohr boiler are few and of large bore.

The design allows for the loss of metal at each penetration leading to considerablythinner drum shells than bidrum boilers.

– Bidrum boilers have many small tube penetrations so it is necessary to design thedrums on their ligament efficiency. This can double the metal thickness. Thin drumwalls reduce thermal stress during the light up cycle.

– Even and thin metal thickness of the drum means that drum distortion during lightup is minimal

– Downcomers are large and uncooled. Steam bubbles forming at pressurefluctuations and high load change can not endanger water circulation.

Self Supporting Construction– Thermal expansion is from bottom to top. This is an advantage with grate firing

because the expansion difference between boiler and grate is minimal. With tophung designs sealing between grate and boiler can be difficulty.

Low Pressure variations at Load Changes– Quick Load variations are possible without significant changes of steam pressure– Water level in the drum remains calm compared to other boiler designs

High Steam Purity– Steam separation system takes place in the drum and external to the drum in the

large bore overflow pipes and steam headers. High steam purity can be achievedeven with poor water quality

Economical space requirements– The design using external downcomers allows heat exchangers to be located some

distance from the drum allowing compact arrangements to be designed– Compact designs have been developed which allows completed boilers to be

delivered to site in one piece.

References– The ERK boiler has 6000 references around the world firing all fuels with many

Biomass and many Waste Fired units mainly in Europe. The reference plants havebeen built by other Eckrohrkessel licensees and all information and experience onthese plants transfer to DGA via the ERK licence system.

– DGA/BIB/Sbang have a number of ERK boiler references which have beenconstructed over the past 15 years, most recently

• The 60 tn/h boiler for APK at Hat Yai• The 45 tn/h boiler at Natural Palm• The 45 tn/h boiler at Clover Prae .(in construction)• The 30 tn/h boiler at CBE Project Pitsonuluk (In construction)

SUITABLE FUELS FOR THE DGA ECKROHR BOILER

The following Biomass fuels are suitable for firing on a Vee grate in a DGA Eckrohr Boiler

• Palm Wastes, fibre, shell, trunk, EFB and similar fuels such as coconut wastes• Rubber Wood slab and stump• Rice Husk• Bagasse• Casava Rhizome• Sugar Trash• Giant King Grass and similar grasses• From Eucalypus Tree

• Wood chip• Fresh bark

• Bituminous Coal

The following Waste Fuels are suitable for firing on a Vee Grate in a DGA Eckrohr Boiler

• Refuse Derived Fuel (RDF) from a suitable treatment system• Reject biomass from RDF plant after treatment typically by the Bio-Dry system

to reduce moisture content to c 30%

Combustion RequirementsSize ConstraintsThe fuel must be sized in accordance with DGA Product Sheet Fuel Sizing for DGA Grates

LCV constraintsDGA will advise the ability of the DGA Eckrohr boiler to handle any waste or Biomass fuelfrom an accurate ultimate analysis of the fuel, inclusive annual variations of MoistureContent. From this DGA calculate a real LCV which must meet the following requirements :-

• LCV must be better than 4500 kJ/kg if superheat steam required• The Moisture content of biomass must be lower than 55%

The boiler will be fitted with a flue gas air heater if high air preheat is necessary due to lowLCV. This can be as high as 300 C on the standard grate allowing wetter fuel to be burned.

Emission ConstraintsThe emissions must meet the Emission Criteria published by the Government. DGA targetthe EU WID limits to ensure a comfortable compliance.

Mainly relevant to RDF fired plants, if the Ultimate Analysis show that any of the followingare high, then an upgraded gas scrubbing system is required

• Sulphur and Chlorine contents• Heavy Metals• Dioxin and Furans

/

A 30 tn/h DGA Eckrohr Boiler in construction for SBANG Corporation for their Project atCBE Project at Pitsonuluk.

The Diagram shows features of the boiler Including the withdrawable Vee Grate, thependant superheater in the 2nd pass, and the overall compact design of the ERK boiler withhigh Temperature air heater and economiser

With more than 6000 boilers installed around the world users can take reassurance thatthey have made the right choice of boiler.

The single drum design with DGA’s Vee Grate is a winning combination.

TYPICAL ARRANGEMENT OF A DGA ECKROHR BOILERFIRED BY A VEE GRATE

DGA VEE (Vibrating Combustion) Grates have been developed as a grate capable offiring all biomass solid fuels, from palm oil waste through wet bark and wood wastes toclean wood chip and even bituminous coal

Fuel SpreadingFuel is spread through the flames already established on the grate to cause ignition ofthe incoming fuel. The ignited fuel lands on the grate adding to the established fuel bed,and the action of the grate moves the whole fuel bed towards the front of the grate wherethe ash discharge conveyor is located.

Gentle WearThe vibrating action of the grate moves the fuel bed gently down the grate with littlewear to the grate surface. The vibrating causes the fuel to be spread to an even depth onthe grate and together with the air drafting dislodges the ash particles from the live fuel.Denser ash falls as bottom ash to the ash discharge conveyor.

High Air PreheatBecause there are no moving or rotating parts in the combustion airbox high levels of airpreheat are available to allow combustion of even very wet biomass fuel.

Handles sticky fuelsThe combustion deck of the grate is water cooled in order to stop fuels from sticking tothe grate during combustion and also to retain the physical strength of the constructionmaterial.

Low Vibrated massAttention has been given to reducing the overall vibrated mass so the grate is builtaround a space frame in light clad material. In order to reduce the impact of the vibration.

Good CombustionCombustion of solid fuel is the major part of the design of this grate so it has beendesigned for good distribution of combustion air, injected at optimum pressure forgood air:solid mixing on the grate..

High Thermal RatingUp to 2 MW/m2 is available for most biomass fuels. This reduces to ~ I.2 MW/m2 withlow calorific value low reactivity coals

High EfficiencyThe main feature of the grate is that it forms the heart of a modern high efficiency firingsystem, that is able to burn a variety of biomass fuels, sized for < 80 mm particleswith good fuel burn out ie low carbon in ash, even when fired at low excess air.Standard grates are available to operate at 45% excess air and with staged aircombustion this can reduce to ~ 30 % excess air.

PRODUCT DESCRIPTION P 201.2

ADVANTAGES OF THE VEE GRATE

DGA Co Ltd, Tel. No: 02 674 3077; E mail : dga@dga.co.th; www.dga.co.th

This picture was shot through the peepholeof a furnace whilst the boiler was firingat high load on Palm Empty Fruit Bunch

The stack was clear.

Vee Grates are supplied by :-

DGA Co Ltd315/344 Soi Wat Po ManSathupradit Rd, YannawaBangkok, Thailand

Tel No. : +66 2674 3077Website : www.dga.co.th

Other Equipment

Ancillary Equipment that may be supplied with the Vee Grate are :-

• Spreader Stokers for Biomass. These are also used for waste materialssuch as RDF.

• Mechanical Spreaders for coal and lump biomass• Variable screw feeders for biomass and or solid fuel• Wet ash discharge conveyors• Vibrating sequence Control

The range of grates available currently spans from 7 MW thermal to 175 MW thermal. Thisis the equivalent of firing steam boilers rated from 10 to 200 tn/h of steam.

More than 30 Vee Grates are operating primarily on Mackenzie Boilers for use in their PalmOil Boilers and latterly on boilers supplied by Bangkok Industrial Boilers of Thailand.

The Vee grate has been installed on boilers through Malaysia, Indonesia and Thailand.Recent projects have been quoted in Africa and Cambodia.

PRODUCT DESCRIPTION P 201.2

ADVANTAGES OF THE VEE GRATE (cont)