Objective
To demonstrate the practical properties of the R12/R114 coolant mixture in a high capacity +/- 3500 heat pump, and to show the reliability of the individual components for process control, with close time tolerances. Special attention will also be given to the newly developed diesel-gas engine with hot cooling and the oil injected screw-type coolant compressor.
Only by operating an installed system can it be determined whether the calculated degree of energy utilisation can really be achieved.
However, during the review period (1.7.84 to 30.6.86) the potential operator could not supply information on the exact temperatures in the individual tanks. In order to arrive at an optimal heat pump design, it was necessary to calculate the water quantities removed from, and fed to the individual tanks for the process and also the heat quantities. For this purpose, a temperature plot was provided on the process cycle of the feed and return flow temperatures at the crystallizer. From this information it was possible to determine which tank was being emptied or filled. With the help of a computer program written for this application and these data, the heat input into the hot water tanks and the heat removed from the cold water tanks, were calculated. The heat pump was then designed on the basis of this data.
On the basis of the small chemical/technical changes involved in the process it was not possible to use the heat pump. To compensate for this, the temperature was then raised so such a level, that tank B14 could be heated. However, since the vaporization temperature remained unchanged, high drive power was required.
The economy of the plant diminished and this, in conjunction with falling primary energy prices, resulted in an amortisation period in excess of five years, even when subsidies are taken into account.
The potential operator has informed the contractor that the project will not be completed, at least for the time being.
A refrigerant R12/R114 mixture will be used for the first time in a large heat pump. Compared with the R114 refrigerant, which is used for temperatures above 80 deg. C, the R12/R114 mixture offers the following advantages:
- it is possible to obtain smaller mean temperature differences and consequently higher output. - the volumetric heating capacity can be varied by varying the R12/R114 ratio. Thus for a specified heating output it is possible to use the optimal speed range.
- conversely, with a constant speed it is possible to vary the heating output by varying the mixture concentration.
- the volumetric heating capacity of the R12/R114 mixture is smaller than that of R114 so that a smaller compressor can be used.
No table or diagrams exist for the mixture, consequently it will be necessary to run tests for certain mixtures.
The heat pump is used to transfer heat from one water tank to another or even from one layer to another layer inside the same tank. This water at various temperatures ranging from 50 to 90 deg. C is used for a undisclosed chemical process.
The heat pump of 3,4 MW thermal rating will use a favourably-priced screw type compressor. It will be driven by a diesel gas engine operating on coke oven gas. Heat from the cooling water and from the exhaust gases will be used to heat the process water from 90 deg. C to 98 deg. C.
The heat pump is integrated into the existing plant in such a way that it maintains the temperature difference of the most heavily used tank (B.13). The cooling water heat from the hot-cooled engine, and the waste heat are coupled to tank B.14 with the water flow being controlled in such a way that it returns to the tank at 98 deg.C.
Topic(s)
Call for proposal
Data not availableFunding Scheme
DEM - Demonstration contractsCoordinator
8000 MÜNCHEN
Germany