Plate & Shell Heat Exchangers – Type XPS

Plate & Shell heat exchangers combine the, compact and countercurrnt, advantages of plate heat exchangers (Plate), coupled with the high pressure ratings of shell and tube heat exchaners provided by cylindrical shells (Shell). So, the best of both worlds. Heat transfer surfaces of 1 m² to 1000 m² enables thermal performance ranges from 10 kW all the way up to 100 MW (obviously dependant on the temperature driving force). The design parameters range from full vacuum to 400 bar (5,800 psi) and from -200 °C to 500 °C, so cryogenic LNG duties all the way to some gas turbine exhaust temperatures with everything else between.

  • high performance with small surface area, weight and footprint by high heat transfer coefficients – reducing structural steelwork and facilitating skid assembly
  • close temperature approach between the hot and cold side by multipass media, providing high heat recovery
  • plate design provides a high wall shear stress, which acts as a self-cleaning effect – reducing fouling and extending the time between cleaning
  • small installation and surface area due to compact design
  • Low cost for steel structures and foundations by a low weight of the equipment
  • fully welded design eliminates gaskets, ensuring high reliability and resistance to failure and leakage, as often experienced with gasketed plate and frame units
  • wide range of plate materials provides high corrosion resistance
  • low liquid inventory provides a rapid start-up and a fast response to changes in process set points and upsets
  • range of plate and nozzle sizes, combined with flexibility of shell design and number of nozzles provides optimized solution
  • shells can be tailored to increase the volume, for evaporating and condensing duties, such as kettle reboilers

Designs of XPS – heat exchangers

Plate Pack

The "heart", the core component, of Plate & Shell heat exchangers is the plate pack.

GESMEX is the technology leader in the production of laser-welded cylindrical plate packages. Welds with large cross connection zones, but low heat input lead to outstanding product quality, and high integrity even in tough working conditions.

The configuration of the plate packs is done with a number of parameters: Size, number of plates, number of passes, plate thickness, corrugation pattern, plate material, arrangement of the plate pack in the shell, and flow guidance.

Function of Plate & Shell heat exchangers

Basic configurations: Heater & Cooler

XPS plate heat exchangers can be easily configured for heating and cooling of both liquids and gases. The heating or cooling media can be put on the plate or on the shell side. For maximum heat transfer media are arranged in countercurrent flow, for pressure-loss-optimized applications cross flow is preferred. When the thermal duty requires a large thermal length (high NTU), then a multi passes configuration is required. Heating steam is usually on the shell side as larger connections reduce pressure drop on the vapor side and smaller nozzles are possible for condensate outlet.

counter flow, single pass
size: XPS 100

cross flow, single pass
size: XPS 50

counter flow, multi pass
size: XPS 50

steam heater
size: XPS 50

Heat exchangers in basic configuration, for which the codes for pressure equipment apply only, with standard parts made of carbon steel or stainless steel, in pressure classes PN 6 to PN 40 are available with short lead times.

Additional customer specific or project specific requirements on design, manufacturing, testing or on documentation of the heat exchangers require individual adjustment of the delivery time.

Heater & Cooler in openable design

When the plate pack is required to be removed from the shell for service work or inspections, Plate & Shell heat exchangers can be configured in an openable design. In this case the plate pack is connected to the shell by a girth flange. This product variant is also used when spare plate packs are held on stock to enable a rapid turnaround during short shutdowns of the plant.

The sizing and configuration of heaters and coolers in openable design follows the same criteria as for fully welded units.

counter flow, openable
size: XPS 100

cross flow, openable
size: XPS 100

openable at both sides
size: XPS 100

Evaporators

Due to the circular shape and highly effective heat exchanger plates, XPS plate heat exchangers are generally well applicable for evaporation duties. Depending on the specific duty the design of the heat exchangers can vary greatly.

The individual sizing and configuration of the heat exchangers is dependent on the following questions:

  • evaporation of pure media or mixtures?
  • complete evaporation or partial evaporation?
  • evaporation at elevated pressure or under vacuum?

Distinguishing design features of GESMEX - evaporators are:

  • the placement of the plate pack in the shell: centrally or eccentrically
  • the orientation of the heat exchanger: horizontal, vertical or sloped
  • shell with integrated knockout pot (dome), internal or external droplet separation.

flooded evaporator
with knockout pot for droplet separation
size: XPS 50

flooded evaporator
with external droplet separation
size: XPS 100

partial evaporator, multi pass
vertical orientation
size: XPS 200

cascade evaporator
installation with slope
size: XPS 100

secondary steam generator
kettle type
size: XPS 100

vacuum evaporator
multi heat packs in the shell
size: XPS 50

Condensers

Round heat exchanger plates in XPS plate heat exchangers are also suitable for condensing duties. GESMEX condensers work as a total condenser, partial condenser or gas dryer, by cooling of water vapor below the dew point. The vapor is normally on the shell side, which provides larger inlet connections and flexability with smaller condensate nozzles.

Beside pure condensation, steam desuperheating and condensate sub-cooling can be combined all in one unit.

The design features of Plate & Shell condensers vary greatly, according to the media and operating conditions. Typical features are:

  • large vapour inlet nozzle sizes (up to 1,000mm), smaller nozzle for full condensation liquid outlet
  • integrated vapour-liquid knockout put for partial condensers ensuring good separation of the liquid and gas phases
  • separate nozzles for removing non-condensed gases and condensate.

The heat exchangers can be fully welded or openable, countercurrent or in cross flow, with single or multi-pass on the plate side.

gas dryer
size: XPS 50

total condenser
size: XPS 150

partial condenser, multi passes
with liquid collector / separator
size: XPS 200

Sizes and Dimensions

GESMEX supplies Plate & Shell heat exchangers in five sizes, with material thicknesses of the heat exchanger plates from 0.6 to 2.5 mm and with different corrugation patterns.

see also: Function of Plate & Shell heat exchangers

The heat exchanger diameter and its length vary depending on factors such as the maximum allowable pressures and temperatures, the thickness of the plate material and the corrugation depth.

Materials of XPS – Heat Exchangers

Flow directors are fabricated from the same material as the plate. No elastomers are used in XPS heat exchangers. Fully welded units are totally gasket-free. The standard configuration of openable heat exchangers is with graphite tanged steel flat-ring gaskets.

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XPS

XPS – Plate & Shell heat exchangers are highly suitable for heat transfer between liquids and gases or for evaporation and condensation duties. The gasket-free and cylindrical design allows operating pressures from full vacuum to 400bar and temperatures ranging from -200 to 500°C.

XPT

XPT – Thermoplate heat exchangers can handle dirty media and show low pressure drop even with high volume flows. The all welded plate-pairs are used from vacuum to 60 bar and from -200 to 800 °C.