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Heat Transfer Products
Graham Corporation
Contact : China Subsidiary
Tel : +86.512.6288.7530
Email : rhagen@graham-mfg.com
Web : www.graham-mfg.com
  Heat Transfer Products
Heliflow Spiral Tube Heat Exchangers

The Graham Heliflow Heat Exchanger is uniquely designed and engineered to handle difficult heat transfer applications. Graham created the Heliflow to be exceptionally versatile, yielding heat transfer rates that can be more than 40% better than typical shell and tube designs. The Heliflow Heat Exchanger encompasses a spiral coil, comprised of multiple parallel tubes mounted within a casing. The case/coil construction creates a spiral flow path providing true counterflow. Each application is specially engineered for an optimal balance of thermal and hydraulic requirements, resulting in maximum heat transfer efficiency. High pressure, specialized materials, cyclic operation, temperature extremes and other conditions can be handled without a problem. The Graham Heliflow Heat Exchanger has years of proven service, in thousands of applications throughout the world, with high quality performance always guaranteed.

Advantages

The tubes in the Heliflow are arranged in parallel, starting with an inlet manifold on one end, and terminating at an outlet manifold on the opposite end. The tube bundle is wound into a helical pattern. This coiled construction creates a spiral flow path for the fluid inside the coil.

Each tube is in close contact with the tube above and below it. The coiled tube bundle is fit into a two-piece casing. When the casing is tightened, it is designed to slightly compress the tubes. Because of the tight fit, the shellside fluid is forced to circulate in a spiral pattern created by the open spaces between the coils.

Advantages of Graham Heliflow Spiral Tube Heat Exchangers

  • Higher efficiency
  • Easy to maintain
  • Accommodates pressures up to 15,000 psig
  • High reliability
  • Code compliant
  • Easily customized
  • Low flow rates
  • Compact design
  • Withstands 500 deg. F temperature difference between fluids
  • Varied material choices

Applications

The many advantages of the unique Graham Heliflow make it an efficient heat exchanger for a wide range of applications; some of which include: 

  • Liquid-to-liquid
  • Cryogenic
  • High pressure
  • Clean steam generators
  • Blowdown
  • Natural gas heaters
  • Vent condensers
  • Mechanical seal coolers
  • Compressor inter/aftercoolers
  • Supercritical fluid
  • Feedwater preheaters
  • Lethal service
  • Steam or process fluid vaporizers
  • Boiler or process sample coolers
  • Hot water heaters
  • High temperature
  • Freeze condensers
  • Hydraulic/lube oil coolers
Desuperheaters

Graham Desuperheaters are used to lower the temperature of superheated steam. They can maintain a set outlet temperature when flow rate or pressure varies. Graham fabricates custom Venturi or Steam-Atomizing Desuperheaters for industries that include power, refining, pulp and paper, food and beverage, plastics and pharmaceuticals. Each Graham Desuperheater is custom-engineered and built for the specific application, ensuring trouble-free service for years.

Advantages

Graham fabricates custom Venturi and Steam-Atomizing Desuperheaters for industries such as power, refining, pulp and paper, food and beverages, plastics, and pharmaceuticals. All our desuperheaters are custom built for each specific application, ensuring trouble-free service for years.

Our Desuperheaters are "in-line" units with flanged, buttweld, or NPT connections, shipped fully assembled and ready for immediate installation. In addition to the company's ISO-9000 quality program, our desuperheaters can be stamped for ASME pressure vessel standards or fabricated to ANSI piping standards.

Graham Venturi Desuperheaters, which use a venturi nozzle to atomize the cooling water, are available in two styles: Double-Venturi (SV-1) and Single-Venturi (SV-2). The SV-1 is our most common style, with a venturi spray nozzle inside a venturi pipe. This style is capable of moderate turndown up to 10:1, low outlet superheat, and moderate pressure drop. The SV-2 is a scaled-down version of the SV-1, with only a venturi nozzle installed in a standard pipe. Turndown capability is much lower at 3:1 and outlet superheat is higher, but this style induces no pressure drop.

Our Steam-Atomizing (SA) Desuperheaters use high pressure steam to atomize the cooling water. Turndown can be very high, up to 50:1, outlet superheat is low, and pressure drop is negligible.

Advantages of Graham Desuperheaters

  • Range of maximum turndown ratios
  • Minimal pressure drop
  • Compact designs
  • Design code compliant
  • Range of outlet superheat capabilities
  • Variety of standard materials
  • Horizontal or vertical orientation with upward flow

Applications

The Graham Desuperheater can be found in a variety of applications, including:

  • Power generation
  • Process controllability
  • Thinner pipe and lighter flanges
  • Preventing lubricant degradation
  • Protecting downstream equipment
  • Gas desuperheaters

Power generation
Boilers running at reduced loads, or with high cycling, produce variable temperature steam. Graham Desuperheaters can stabilize superheat over wide flow ranges.

Surface condensers work most efficiently when supplied with saturated steam. This eliminates the need to add tubes for cooling superheated steam, and prevents stresses caused by thermal expansion when hot, dry steam enters the condenser.

Turbine bypass systems require systems of pressure reducers and desuperheaters to reduce the pressure and temperature normally handled by the turbine.

Process controllability
Graham Desuperheaters can help control a variety of processes. If steam temperature is not constant, a process may become uncontrollable, especially when steam flow or pressure fluctuates. This can impact product quality, force unscheduled downtime, create personnel safety issues, and cost a great deal in repairs and replacements.

Thinner pipe and lighter flanges
Cooler steam can require thinner pipe schedules or smaller flange classes than superheated steam. Aside from lower costs, this can reduce lead times for piping, valves, controls, and other equipment during initial construction or shutdown maintenance.

Preventing lubricant degradation
Superheated steam may quickly degrade certain lubricants, so saturated steam is preferred for expensive specialty items such as pumps and compressors.

Protecting downstream equipment
Some metals are not suitable for high temperature service, but desuperheated steam often allows use of carbon steel and lower grade alloys instead of stainless steels and high-grade alloys, which are often necessary at high temperatures.

Properly designed desuperheaters ensure complete atomization of water droplets, and thorough evaporation and mixing downstream. This prevents damage to elbows, valve seats, heat exchanger tubes, other downstream equipment, and even some products

Gas desuperheaters
Desuperheaters are usually designed for steam cooling, but the same principles apply to any vapor. Graham has decades of experience designing and fabricating gas desuperheaters. Recent applications include methanol, toluene, natural gas, R-134a, and air. We can also design for any mixture of gases required.

Plate Heat Exchangers

The Graham UltraHeat Gasketed Plate Heat Exchanger line is engineered for optimum performance in any given application. Whether the goal is to maximize heat recovery or to cool even the most viscous of slurries, Graham engineers can custom-design an UltraHeat Plate Exchanger configured to specific needs.

The Graham MicroHeat line of Brazed Plate Heat Exchangers combines high performance with low cost. The heavy duty construction and compact design lends this heat exchanger to a variety of applications. The materials of construction are corrosion resistant 316 stainless steel plates and connections, and copper or nickel braze. The brazing process eliminates gasketed joints which allows for higher design pressure and temperatures.

Advantages

Plate heat exchangers consist of a series of corrugated plates hung from a carrying bar and clamped between fixed and movable heads. The heat transfer plates are normally manufactured in stainless steel, but are available in other materials.

In Gasketed Plate Heat Exchangers, each heat transfer plate is fitted with an elastomeric gasket, which seals and distributes the process fluids. The heads, normally referred to as channel covers, include connections to permit the entry of the process fluid into the plate pack.

In Brazed Plate Heat Exchangers, the brazing process eliminates gasketed joints which allows for higher design pressure and temperatures.

The channel formed by two adjacent plates is the key to the plate heat exchanger's high efficiency. The hot and cold fluids are distributed through alternate channels in a counter-current arrangement. This counter-current flow provides for maximum thermal efficiency. The flow pattern induces turbulence at very low Reynolds numbers, which also contributes to high heat transfer rates. Units are custom selected to effectively optimize the available pressure drop.

The fluid shear stresses in a plate exchanger are much higher than those of a tubular exchanger. This tends to keep the channels in a plate exchanger much cleaner. For clean services, the normal practice is to provide units designed for 100% of the surface area required. For fluids that foul, plate exchangers can be provided with 5-10% excess area.

Plate heat exchangers are well suited for applications that require close temperature approaches. (The approach temperature is defined as the hot fluid outlet temperature minus the cold fluid inlet temperature.) Units can achieve temperature approaches as close as 2 degrees F.

Advantages of Graham Gasketed UltraHeat Plate Heat Exchangers
Economical, low-capital investment
,Easy to install
,Heavy duty
,Low maintenance costs
,Compact modular design
,Advantages of Graham MicroHeat Brazed Plate Heat Exchangers
High performance
,Higher design pressure and temperatures

Applications

Plate and frame exchangers offer the highest efficiency mechanism for heat transfer available in industry today.  Some of the applications where this high efficiency is evident when using the Graham Brazed or Gasketed Plate Heat Exchangers are:

  • Water heaters
  • Cooling tower isolation
  • Free cooling
  • Waste heat recovery
  • Heat pump isolation
  • Thermal (ice) storage systems

Water heaters
Graham plate exchangers are an excellent choice for heating potable water or other fluids, utilizing steam or high temperature water. The high heat transfer rate and corrosion resistance of stainless steel plates make these units ideal for heating service.

Cooling tower isolation
Many operators recognize the benefit of isolating the cooling tower water from the building circulating water system. Particles trapped in cooling tower water can rapidly plug or foul chillers or other building heat exchange systems. The high turbulence in a Graham GPE Series plate will minimize fouling. Should the plate become plugged, it can be disassembled and cleaned when conditions warrant. This provides plant maintenance personnel a single site that is easy to clean, rather than numerous sites throughout the building system.

Free cooling
Many areas experience extended periods when the ambient air temperature is significantly cool to provide for free cooling. During these periods, the cooling tower water will be able to pre-cool entering air, assist in mechanical cooling, or provide total system cooling for the air conditioning system. When operating in the "free cooling" cycle, the plant air conditioning chillers may be shut down, greatly reducing plant utility costs. A Graham GPE Series plate exchanger is an integral part of a free cooling system.

Waste heat recovery
Reclamation of waste heat can significantly reduce energy costs. Waste heat generated by steam condensers, chillers, and other processes can be used to heat make-up water or air. The high efficiency and close temperature approaches possible with the GPE Series plate exchanger can be utilized to reduce overall energy costs.

Heat pump isolation
To protect the heat pump from contaminants contained in the water supply, a Graham GPE Series plate exchanger is often used. Many water sources contain suspended and dissolved solids that can foul and decrease efficiency of the heat pump. The Graham plate exchanger maintains a high degree of turbulence that is essential for maintaining high heat transfer rates and reducing fouling.

Thermal (ice) storage systems
Thermal storage systems offer an efficient method to reduce energy costs. This is accomplished by utilizing chiller capacity during off-peak periods, when lower electricity rates are in effect. Brine or ice in storage tanks is cooled during this time for use when the cooling load dictates. Graham GPE Series plate exchangers allow for the efficient transfer of this stored cooling capacity to the distribution system.

MicroMix II / MicroMax Water Heaters

Graham has engineered two different types of indirect fired instantaneous Water Heaters to meet the stringent demands of both comfort and process hot water heating. They combine the superior design and efficiency of our Heliflow heat exchanger or UltraHeat plate and frame exchanger with our special 3-way blending valves. The result produces the right amount of water, at the right temperature, under widely varying demands.

The patented MicroMix II and MicroMax use a unique feedforward temperature control system to instantly produce hot water within +/- 4 F. of the set temperature. Their outstanding performance is confirmed by the many installations in hospitals, schools, hotels, restaurants, laundries, ships, factories, and food plants.

Advantages
Graham MicroMix II water heaters use steam to instantly produce up to 120 gallons per minute of hot water, yet have a footprint less than 6 square feet. These units combine our highly efficient, compact Heliflow heat exchangers with our special 3-way blending valves. Each MicroMix II is capable of supplying hot water at a set temperature at flow rates up to the maximum capacity of the unit.

The unit consists of two main components, the heat exchanger and the blending valve. The blending valve is a 3-way valve which mixes cold water with overheated water to provide the outlet temperature desired. A portion of the cold water is admitted to one port on the valve, while the remainder traveling through the heat exchanger is overheated, and then flows to the port of the valve. The valve plug is positioned to allow proper proportions of cold and overheated water to mix. The steam never comes into contact with the water.

The blending valve incorporates a diaphragm that responds to changes in differential pressure. Above the diaphragm, supply water pressure is introduced via a sensing line. Below the diaphragm is the downstream water pressure. During no flow conditions, the pressure on both sides of the diaphragm is equal and the valve plug is in the closed position. As demand for hot water occurs, instantly the pressure differential forces the diaphragm, valve stem, and valve plug to travel into the open position. The greater the demand, the larger the pressure differential will be. The valve plug opens or closes corresponding to demand. Accuracy is +/-4 degrees F through all flows.

Even when flow demands change rapidly, the outlet water temperature is maintained with no overshooting or undershooting the desired temperature.

Graham MicroMix II Water Heater Advantages
,Compact design
,Ease of installation
,Self-contained
,Code compliance
,Accessories
,High efficiency
,Quality assurance
,Options

Applications
Graham MicroMix II / MicroMax water heater units are used anywhere hot water is required, as long as steam is available. Most commonly, they have been supplied for shower systems in universities, hospitals, governmental facilities, hotels, apartment complexes, and institutions.

Other applications for Graham water heaters include:
,industrial safety showers/eye wash stations
,wash down systems
, jacket heating systems
,lavatories/showers
, cafeterias
,process heaters
,food processing
,pulp & paper
,pharmaceutical

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