Cleaner Technology Projects in Denmark 1997
Elimination of Organically Loaded Waste Water from Organic Batch Production
Elimination af organisk belastet spildevand fra organisk batchproduktion
Arbejdsrapport nr. 18, 1997, Miljøstyrelsen
The general purpose of the present report is to design and produce a functional Full-scale plant for recovery of minimum 14 tonnes of organic solvents and reduction of A/S GEA’s consumption of water by 2,000-3,000 m³ per year. The plant is constructed on the basis of knowledge from the first part of the project, which describes the conversion of the vacuum pumps from operation with water to oil. In the first part of the project the plant was tested in pilot scale with success. This report deals with the design and the production of the full-scale plant.
The project can be divided into three sections:
 | The dimensioning, design and control of the full-scale plant |
| The physical construction, tests and evaluations of the plant |
| The reporting on the co-operation between the participating parts |
The dimensioning and design of the plant are based on a number of compromises and limitations, which are the results of theoretical, physical, and economical possibilities and limits. Hitherto, every single technical element of the plant has been well known, while the combination of and the interaction between the single parts had to be examined. For the construction of the plant the following materials were used: 1 km of rustproof and acid-proof pipes, approximately 100 valves, pilot wires, pumps and other equipment.
The tests with the plant have turned out successfully. The over-all impression of the plant can be described as follows:
As compared with earlier disposal of approx. 16.5 tonnes of solvents per year to waste water and air, approx. 15 tonnes of solvents per year are now expected to be collected. The remaining 1.5 tonnes are disposed to the air. The collected solvents are expected to be re-cycled in processes where the quality of solvents is not critical. A recycling percentage of maximum 80% is expected.
The vacuum pumps have successfully been converted from operation with water to oil. The water consumption of 2,000-3,000 m³ per year has been eliminated completely.
Moreover, it is also estimated that the plant can eliminate and collect solvents with low and medium steam pressures satisfactorily. The disposal of solvents to air at maximum production is less than 2 kg per ton.
The plant can deal with single productions of solvents with high steam pressure. However, the plant cannot deal with many productions in which there are solvents with high steam pressure simultaneously, as the disposal of solvents to air would be to excessive.
The efficiency of the plant is dependent on a number of conditions. Most important for obtaining good results are the kettle’s and pipe system’s air-tightness under vacuum. If the tightness is improved, the disposal of solvents would drop accordingly and, to a higher extent, it could be used for productions with solvents with high steam pressures. If the air oozes in to the kettle and the pipe system, the disposal of solvents will increase.
From an economic point of view, the operations with the new plant will mean a cost saving in the operating costs of DKK 70,000 per year. The cost saving is a result of reduced expenses for water, drainage, and waste water charges. The recycling of solvents reduces the need for purchase and waste disposal. However, increased energy consumption for cooling of coolant and purchase of oil for the pumps mean increased costs.
Author/ institution
Søren Birch, Ernst & Young A/S
This report is subsidised by the National Council for Recycling and Cleaner Production
ISSN no. 0908-9195
ISBN no. 87-7810-757-1