PHE chiller capacity

[fassi]

Hi list

I may have a capacity problem with a PHE chiller. It is designed for 1050 KW operating on ammonia and gravity recirculation. The evaporating temperature is -10 C and secondary refrigerant is propylene glycol of 35% volume concentration, T-in is + 6 C and T-out is -2 C based on 120 m³/hour. The "riser" between the PHE and the separator is a 6" pipe and is 2,2 m high. The PHE has active heat transfer area of 50,16 m² and 116 plates in total.

For the time being the chiller only need to produce approximately 650 KW, but I cannot achieve T-out of -2C, I get instead + 7C and there in no way to lower this temperature, but I have no problem in maintaining the 8 C differential temperature. The glycol flow is approximate 80 m³/hour.

So I wonder if the 6 " riser is to big for 650 KW capacity and therefore accumulate a certain liquid column which cause a increasing the evaporating temperature.

Looking forward to hear your comments.

Fassi

[US Iceman]

Is the evaporating temperature designed for -10C, or is this what the evaporating temperature currently is operating at?

Also, what is your suction pressure pressure at the compressors?

[Andy]

Hi fasi

a lot of heat exchangers are designed on an 8k td, what is the design in this case.

Have you got a good way of draining oil off the plates and has the glycol specific gravity be tested

Kind Regards Andy

[fassi]

Is the evaporating temperature designed for -10C, or is this what the evaporating temperature currently is operating at?

Also, what is your suction pressure pressure at the compressors?

The PHE evaporating temperature is designed for -10 C and the compressor ( 5 compressors in the system) suction temperture is alson -10 C.

[fassi]

Hi fasi

a lot of heat exchangers are designed on an 8k td, what is the design in this case.

Have you got a good way of draining oil off the plates and has the glycol specific gravity be tested

Kind Regards Andy

The oil is purged automatically 2 times per day from a 20 liter accumulation tank and the glicol concentration has been tested.

But if I cannot "lift" the gas/liquid blend up to the separator because of to low gas velocity in the riser the liquid part will accumulate in the mentioned riser and thus increase the static pressure and therefore also increase the evaporating temperature

[faryuki]

Hi list

I may have a capacity problem with a PHE chiller. It is designed for 1050 KW operating on ammonia and gravity recirculation. The evaporating temperature is -10 C and secondary refrigerant is propylene glycol of 35% volume concentration, T-in is + 6 C and T-out is -2 C based on 120 m³/hour. The "riser" between the PHE and the separator is a 6" pipe and is 2,2 m high. The PHE has active heat transfer area of 50,16 m² and 116 plates in total.

For the time being the chiller only need to produce approximately 650 KW, but I cannot achieve T-out of -2C, I get instead + 7C and there in no way to lower this temperature, but I have no problem in maintaining the 8 C differential temperature. The glycol flow is approximate 80 m³/hour.

So I wonder if the 6 " riser is to big for 650 KW capacity and therefore accumulate a certain liquid column which cause a increasing the evaporating temperature.

Looking forward to hear your comments.

Fassi

Please check the pressure diff. inlet and outlet of your glycol, if the diff. is more then 1 bar you should check your plate condition also the liquid ammonia strainer.

faridz