SCHNEIDER-KESSEL BERLIN ® DAMPF- UND HEIßWASSERERZEUGER

WATER-TUBE BOILERS DEFINITION

The SCHNEIDER-Wasserrohrkessel is a natural circulation boiler without any forced water flow. The Boiler is designed as a water-tube boiler for steam and hot water generation.

ADVANTAGES

The unique advantages of the SCHNEIDER-Wasserrohrkessel are: `Absolute dry steam due to no “carry-over”.

`Stable water level with moderate fluctuation even during sudden load changes.

`Rapid cold start-up and fast load changes as a result of the fast starting water circulation and the unheated drum.

`Compact and selfsupporting design.

`No material stress as result of an unhindered free expanding tube cage which is independent from the unheated drum.

`Adapts ideally to the space available.

`Multi fuel utilization.

EXPERIENCES AND KNOW-HOW

SCHNEIDER-KESSEL BERLIN profits from an excellent know-how gathered from the experiences from over 6000 boiler plants devlivered according to the corner tube boiler design principle.

CUSTOMER FOCUS

Typical industries where we supply Eckrohrkessel:

`Chemical, Petrochemical and Oleo-chemical Industry `Pulp & Paper Industry `Rubber Industry `Pharmaceutical Industry `Food and Beverage Industry `Industrial Power Plants `District Heating Plants DESIGN

The pressure part consists of a rectangular and stable frame work of down comers, collectors and distributors. They are welded together in tube-wall-tube design forming a gas tight tube cage.

10 9 5 8 1 steam drum 1 4 2 down comer 3 bottom tubes 4 upper collector 5 over flow tubes 7 2 6 6 return tubes 7 riser tubes 8 mixture tubes 9 partition wall 10 steam outlet 11 lower collector 11 3

THE WATER CIRCULATION SYSTEM

The water circulation system of the SCHNEIDER-Wasserrohrkessel has a number of special characteristics which distinguishes it from all other known natural circulation water tube boilers, especially from the Bi-Drum design.

In the SCHNEIDER-Wasserrohrkessel design only the riser tubes (7) and the bottom tubes (3) are heated whereas the drum (1) and all down comers (2 & 6), the mixture tubes (8), the overflow tubes (5) and all collectors are unheated.

The water-steam mixture, generated in the heated riser tubes (7) and the bottom tubes (3) flows upward into the unheated upper collector (4) and from there to the unheated mixture tubes (8). In this section of the boiler an almost complete separation of steam and water occurs. From here the separated steam flows through the overflow tubes (5) into the drum area behind the partition wall (9) above low water level LWL. An almost 50% portion of the separated water flows through the unheated return tubes (6) down to the heated bottom tubes (3) and the remainder via the mixture tubes (8) into the drum area behind the partition wall (9) below low water level LWL from where it returns through the down comer tubes (2) back to the unheated lower collector distributor (3) and the cycle starts again.

In all other known water tube boiler designs, especially the Bi-Drum design, the extracted steam is generated some- where in the system and rises from the bottom of the drum through the water level resulting in fluctuation of the water level along with the risk of a high percentage of “carry over”. HIGH STEAM PURTIY

The reason for the unrivalled high steam purity is the unique design of the SCHNEIDER-Wasserrohrkessel. The steam is completely generated outside of the drum and flows into the drum via overflow tubes behind the parttion wall and above the water level. From there the extracted steam flows behind the partition wall to both ends of the drum where it turns back and flows in front of the partition wall to the steam outlet nozzle which is located in the middle of the drum.

As a result of this long way and the low velocity no moisture remains and the extracted steam is absolutely dry. No “carry over” occurs.

QUICK START-UP

`At start-up the water circulation starts very quickly because there are neither long overflow distances nor long distances from the down comer to the heating surface of the tube cage. Due to the short distances all water filled tubes reach saturation temperature at start-up. Dangerous material stress caused by different thermal expansion will not occur. `There is no lower drum, hence no thermal stress occurs in the bottom area as normally experienced with bi-drum boiler designs due to crooked lower drums during start-up. `A low number of tubes are connected to the drum compared to other boiler types, hence the drum shell is only weakened to a low extent. At same strength the drum shell can be thinner than other boiler drums. `The admissible temperature variation gradient is significantly higher leading to a quick start-up. The shell thickness is constant over the whole circumference. A deformation of the drum does not exist. `The down comer tubes are designed with a large diameter. Steam bubbles emerging during sudden pressure drops at peak loads do not endanger the water circulation and hence do not put the boiler at risk. `Quick load variations are possible without significant changes of steam pressure. `The water level in the drum remains constant during load changes compared with other boiler designs. SELF-SUPPORTING DESIGN

`The totally welded tube cage with all its components such as convection parts, economiser, superheater etc. is supported by the down comer and return tubes which are located in the corners of the boiler. From this design principle the name “Wasserrohrkessel” comes since in one-to-one translation it means “Corner. Tube Boiler”. A heavy supporting frame, where other boiler systems have to be hung in, is unnecessary. Therefore, complicated connections between boiler and cold frame do not exist.

`The thermal expansion is from bottom to top. This is an advantage with grate firing systems because the thermal expansion difference between grate and boiler is minimized. The sealing between grate and boiler is easier.

MULTI FUEL UTILIZATION

SCHNEIDER-Wasserrohrkessel can be operated with a broad range of fuels. Beside traditional fuels such as oil, gas, coal and wood there are special designs where fuels such as industrial waste, municipal waste, paper, biomass and hazardous waste can be utilized. Due to the excellent reaction on quick load variations and the outstanding quick start-up behavior, the SCHNEI- DER-Wasserrohrkessel is the ideal solution for boiler plants operating with heterogeneous fuels.

GOOD FIT TO SPACE REQUIREMENTS

Due to the design principle of down comer and return tubes the heating surfaces are not supplied with only water from the drum. That means that the heating surfaces can be arranged in a distance from the drum. Large boilers, i.e. boilers for combustion of municipal waste, can be easily designed. `Compact types have been developed for various fuels in order to apply to limited space on site. `Very often compact types up to capacities of 200 t/h and more can be delivered in one piece. `Boiler with bigger capacities can be fabricated in segments in the workshop. On site only little welding is necessary leading to short erection times and high quality. FOR SMALL CAPACITIES

Model of the HP series This boiler model of horizontal design is especially developed for small capacities of up to 20 t/h, but high design pressures of up to 100 barg (corresponding to a saturated steam temperature of approximately 320 °C) finds its application in open steam/condensate circuits in the oil and fat industry where the steam comes in direct contact with the product (e.g.fatty acids).

The HP series boiler is proof against sudden peak loads. Only slight and momentary pressure drops occur with the steam quality remaining unchanged. The reasons for this performance and the unique advantage of this design are:

`absolute dry saturated steam `large thermal energy reservoir because of large water content `short recovery time after sudden peak loads with unchanged high steam quality. `no carry over even during extreme sudden peak loads. `no contamination of products. `steam extraction at operation pressure level secured even when the burner is switched off `perfect temperature control of distillation columns. `burner can be operated continuously to keep the boiler on operation pressure level `all boiler loads can be covered by one boiler due to the boiler high turn down ratio FOR MEDIUM CAPACITIES

SCHNEIDER-Wasserrohrkessel for medium and high capacities provide a secure and dependably solution when it comes to the generation of saturated and superheated steam. Designed for liquid or gaseous fuels or as Waste Heat Recovery Boiler utilizing waste gas behind gas engines or gas turbi- nes SCHNEIDER-Wasserrohrkessel offers the ultimate solution in means of technical flexibility. Typical industrial applications for SCHNEIDER-Wasserrohrkessel designed as steam generator.

`Easy operation and maintenance due to horizontal and compact design. `Easy access to boiler equipment such as burner and fittings as well as to the heating surfaces. `Applicable for all liquid and gaseous fuels. `Dimensions adaptable to limited space on site.

As a hot water generator the SCHNEIDER-Wasserrohrkessel is normally used in far distance heating systems in areas such as North Europe or areas with similar climate conditions. In addition to the before described advantages of the SCHNEIDER-Wasserrohrkessel principle there is one issue that is unique for hot water generators of this design:

`Due to the arrangement of heating surfaces no temperature control of the return water by means of special and costly mixing pumps is required.

FOR LARGE CAPACITIES

Boilers for higher capacities for steam and hot water generation can be delivered for the utilization of various liquids, gaseous and solid fuels. We are able to offer advanced solutions to utilize renewable energy which is in line with the future outlook policy of sustained power supply. Range of capacity:

`steam rating up to 300 t/h `steam pressure up to 135 barg `steam temperature up to 535° C `hot water boiler up to 175 MW SCHNEIDER Engineering GmbH SCHNEIDER-KESSEL (ASIA) LTD. Berlin, Germany Bangkok, Thailand Tel.: +49 (0)30 75 44 93 99 - 0 Tel.: +66 (0)2 3660 - 573 Fax: +49 (0)30 75 44 93 99 - 21 Fax: +66 (0)2 3660 - 574 [email protected] [email protected]

We deliver worldwide

Range of Deliveries and Services Steam and Hot Waters Generators `water tube boilers `three pass boilers `waste heat recovery boilers `electrically heated steam and hot water generators

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www.schneider-kessel.com 08/2013