Introduction to Single Effect Steam Absorption Chillers for Efficient and Eco-Friendly Cooling

Single effect Steam Absorption Chiller

YORK IsoFlow :- Single Effect Absorption Chillers: 120-1377 Tons

Today's environmental and energy considerations demand innovative chiller plant designs which save expensive peak load kW-hours and eliminate CFCs as well in a growing number of applications with waste heat or abundant low pressure steam, single effect absorption chillers offer an ideal means of saving on cooling costs without a significant installation cost penalty.

Applications particularly well-suited for the YORK  lsoFlow Absorption Chiller include the following

Cogeneration -For a number of cogeneration plants, high pressure steam has many valuable uses, while low pressure steam is considerably less useful, yet more plentiful in these plants, the lsoflow absorber can provide cooling with low pressure steam or hot water, freeing high pressure steam for power generation or other valuable uses.

 

Inlet Air Cooling -Use an lsoFlow chiller to cool inlet air to a gas turbine or a compressor. The lowers specific volume associated with cooler air provides more combustion capacity in the summer months

Waste Heat Recovery- Recover waste heat from printing plants, incinerators or gas engine jacket water to introduce the new isoflow to provide required comfort or process cooling at little operational cost.

Commercial Cooling / Peak Shaving -For particularly pronounced peak loads with few operating hours, the IsoFlow absorber's lower first cost may provide an acceptable payback when more efficient. yet more expensive double effect chillers cannot.

 

For these and similar money-saving designs, consider the field-proven lsoFlow design in over twenty years of operation, the YORK single effect design has proven itself in applications ranging from schools to refineries. 

 

  

The York IsoFlow Absorption Chiller introduces are revolutionary system of unit controls and mechanical devices designed to keep the chiller running in even the most extreme circumstances. Old concerns about crystallization are approached with a hybrid of new technology and older, proven methods. Additionally, the IsoFlow chiller contains a host of other features designed to give the machine a long. trouble-free life. The result: the smartest, safest, and most reliable single effect absorption chiller on the market today. 

1.Concentration Limit- York's ISN IsoFlow micro processor control panel actually detects the high lithium bromide concentrations which can endanger the unit. When high concentrations are present, the panel limits heat input until solution reaches equilibrium at a lower concentration. In this manner the machine operates only within the safe and practical limits of the lithium bromide absorption cycle.

2 “ J” Tube – If crystallization were to occur it would begin in the strong solution side of the solution heat exchanger . This would force the strong solution to back up in the generator. at certain generator solution level, the hot strong solution would over flow into J tube. This tube sends hot fluid directly to the absorber, immediately worming the weak solution. the heated weak solution would then warm the crystallized Solution on the opposite side of the heat exchanger. This transfer of heat will cause the crystallized lithium bromide to move back into solution, allowing the unit to continue operation.  

3.Stabilizer Valve -If minor crystallization occurs And causes over flowing the "J tube, the temperature of the "J" tube will increase because of the hot solution. A specially placed sensor detects this change in temperature and the panel sends a signal to open a solenoid on, York's patented Stabilizer Valve. When the Stabilizer Valve is open, refrigerant water is injected into strong solution immediately before the heat exchanger. The water serves to dilute the strong solution, allowing the crystallized lithium bromide to become soluble at a lower concentration.

4. Steam Supply Pressure/Temperature Limit -The ISN IsoFlow control panel actually monitors the inlet steam(or hot water) temperature and steam pressure. The panel will close the control valve to the machine if temperatures or pressures become excessive, thus protecting the machine from potentially harmful conditions.

5.Load Inhibition Before the IsoFlow unit shuts down due to a given safety condition ,it first crosses a warning threshold which will cause the panel to limit heat input to the machine. In this manner, the IsoFlow unit continues its vital task of making chilled water, while allowing operators the opportunity to find system deficiencies before they lead to an actual shutdown.

6.Stainless Steel Pans -Both the pan in the evaporator (which holds refrigerant) and the pan in the generator (which holds hot LiBr solution) are fabricated from stainless steel, giving the machine added protection against corrosion.

7.Magnetic Strainers Since pump bearings are lubricated by refrigerant, the YORK IsoFlow design protects the bearings from foreign matter through the use of a magnetic strainer.

8.Hermetic Pumps -YORK's exclusive hermetic industrial pump design provides low electrical consumption and a long, trouble-free life

9 Double walled Evaporator – The evaporator on each isoflow model is lined with second wall eliminating the need for field insulation.

10. Purge System – Yorks efficient purge system expels non condensable gases from the units external purge chamber without the risk of spilling lithium bromide.

11.Brass Spray Nozzles- Evaporator spray headers use corrosion resistant brass to ensure long life.

12.Stainless Steel Spray Nozzles Absorber spray headers are fabricated from stainless steel, providing trouble-free operation in a particularly demanding environment.

13. Single Power Connection-A single point power connection is all that is required for the IsoFlow the Absorption Chiller, providing further reliability and ease of installation. 

14. 45°F Condenser Water- TheYorkIsoFlow chiller is capable of operating with entering condenser water temperatures as low as45°F. Without proper compensation, lower tower water temperatures cause: low refrigerant level, potential for crystallization, and low refrigerant temperature. The combination of three control systems allow the IsoFlow to maintain a stable balance of solution and refrigerant parameters as entering tower water temperature varies:

 * At low refrigerant levels, the Unloader Control Valve opens to inject lithium bromide into the refrigerant sec line. This maintains refrigerant level preventing pump cavitation and keeps flow available to dilute the concentrated solution.

 • The Steam Valve Override Control System adjusts the steam input regulating the concentration of the lithium bromide leaving the generator to a safe level for the operating temperature of the machine.

•The Stabilizer Valve will open to dilute the absorber concentration the refrigerant temperature drops below a preset level.

The result is a system that maintains proper balance of machine loading, and solution and refrigerant characteristics to allow continuous operation with tower water Temperatures as low as 45°F.

 

 

HOW IT WORKS

The lsoFlow single effect absorption cycle uses ordinary water as the refrigerant and lithium bromide as the absorbent. It is the strong affinity that these two substances have for one another that makes the cycle work. The entire process occurs in almost a complete vacuum.  

1.Solution Pump - A dilute solution (58.5%) of lithium bromide solution is collected in the bottom of the Absorber shell. From here, a hermetic solution pump moves the solution through a shell and tube heat exchanger for preheating.

 2. Generator- After exiting the heat exchanger, the dilute solution moves into the upper shell. The solution surrounding the bundle of tubes which carries either customer provided steam or hot water. The steam or hot water transfers heat into the pool of dilute lithium bromide surrounding the tube bundle. The solution begins to boil sending refrigerant vapor up word into the condenser and leaving behind concentrated lithium bromide (about 65%). The concentrated lithium bromide solution moves down to the heat exchanger, where it is cooled by the weak solution.

3. Condenser -The refrigerant vapor rises through vapor eliminators and strikes the condenser tube bundle. The refrigerant vapor condenses on the tubes, and the heat is removed by the customer provided tower water which moves through the inside of the tubes. the refrigerant water condenses, it collects inside of a trough at the bottom of the condenser.

4. Evaporator- The refrigerant water moves from the condenser in the upper shell down to the evaporator in the lower shell. Due to the extreme vacuum in the evaporator (6mm Hg absolute pressure), the refrigerant water which strikes the evaporator tube bundle boils at 39°F, creating the refrigerant effect. (This deep vacuum is created by hygroscopic action in the Absorber directly below)

5.Absorber As the refrigerant vapor descends to the Absorber from the Evaporator, the strong lithium. bromide solution from the generator is sprayed over the top of the Absorber tube bundle. The strong lithium bromide solution actually pulls the water vapor into solution. This creates the deep vacuum in the Evaporator, and it also generates heat which is removed by customer provided tower water. dilute solution lithium bromide collects in the bottom of the absorber and the process begins once again.

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