Polisie
02-07-2012, 12:33 PM
Hi.
I am busy with a project where we use an ammonia chiller plant. Reason being that the COP is above 7 and power in South Africa is getting more expensive.
Background
The refrigeration system offered will operate on a gravity feed re-circulated liquid ammonia design philosophy, with all ancillary items i.e. plate heat exchanger, compressors, vessels and piping, designed for this application. The refrigeration system has been designed to operate at a suction condition of -1°C and a discharge of 35°C. The main ammonia plant design is based on a single plate heat exchanger undertaking the heat transfer from the water to the ammonia.
The secondary side of the plant is based on individual heat exchangers (Evaporators) undertaking the heat transfer between the glycol and the product/room respectively.
We are running two(2) Bitzer compressors where each unit has a capacity of ± 96 kWR @ -1°C / +35°C @ 1450 rpm.
Question
I do not have a lot of experience on buffer tanks and hotwell/coldwell tanks. We looked at a Buffer Tank but the design engineer is on leave and I am stuck with the decision.
If we go use the Buffer tank we need to fill/pressurise the tank with nitrogen so that the propylene glycol (25%) does not degrade due to oxidation.
We sized it to a Dia600(mm)x1800(mm) high and a maximum pressure of 600kPa. The system will be pressure tested to 600kPa.
1. Is the tank sized adequately?
2. How much nitrogen pressure is required?
3. Or is Nitrogen required?
4. Which is better: buffer tanks OR hotwell/coldwell tanks?
9081
I am busy with a project where we use an ammonia chiller plant. Reason being that the COP is above 7 and power in South Africa is getting more expensive.
Background
The refrigeration system offered will operate on a gravity feed re-circulated liquid ammonia design philosophy, with all ancillary items i.e. plate heat exchanger, compressors, vessels and piping, designed for this application. The refrigeration system has been designed to operate at a suction condition of -1°C and a discharge of 35°C. The main ammonia plant design is based on a single plate heat exchanger undertaking the heat transfer from the water to the ammonia.
The secondary side of the plant is based on individual heat exchangers (Evaporators) undertaking the heat transfer between the glycol and the product/room respectively.
We are running two(2) Bitzer compressors where each unit has a capacity of ± 96 kWR @ -1°C / +35°C @ 1450 rpm.
Question
I do not have a lot of experience on buffer tanks and hotwell/coldwell tanks. We looked at a Buffer Tank but the design engineer is on leave and I am stuck with the decision.
If we go use the Buffer tank we need to fill/pressurise the tank with nitrogen so that the propylene glycol (25%) does not degrade due to oxidation.
We sized it to a Dia600(mm)x1800(mm) high and a maximum pressure of 600kPa. The system will be pressure tested to 600kPa.
1. Is the tank sized adequately?
2. How much nitrogen pressure is required?
3. Or is Nitrogen required?
4. Which is better: buffer tanks OR hotwell/coldwell tanks?
9081