Final Report: Recovery of Catalyst Vapors From Foundry Cold Box Core MachinesEPA Contract Number: 68D99057
Title: Recovery of Catalyst Vapors From Foundry Cold Box Core Machines
Investigators: Morisato, Atsushi
Small Business: Membrane Technology and Research Inc.
Project Period: September 1, 1999 through March 1, 2000
Project Amount: $70,000
RFA: Small Business Innovation Research (SBIR) - Phase I (1999) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , SBIR - Air Pollution , Small Business Innovation Research (SBIR)
Description:Metal casting operations in foundries produce air streams containing 0.5 to 5 vol% of various catalyst vapors. The source of these streams, which are produced at more than 3,000 U.S. foundries, is the exhaust from cold box core machines. The streams are a serious pollution problem, and also represent a significant resource recovery opportunity, because a large foundry may release catalyst vapors with a potential annual value of $500,000. Current treatment options, scrubbing or incineration, are expensive, involve pollution issues, and do not recover the catalyst for reuse. Membrane vapor separation technology, on the other hand, has the potential to recover the catalyst vapor in sufficiently pure form for direct reuse in the cold box machine. The overall objective of this project is to develop such a process.
In the proposed process, the exhaust from the cold box is fed to a compressor, then to a membrane vapor separation unit. The key technical issue addressed in this Phase I project was the identification of a suitable membrane material for the membrane unit.
The project had two specific objectives. The first was to select a suitable membrane material. The membrane had to (i) meet the target performance required for an economically viable process and (ii) be stable in the presence of catalyst vapors. The second objective was to perform a technical and economic analysis of the process by preparing a realistic system design based on the membrane permeation data obtained for the new membrane and by estimating the system cost and performance. Both objectives were met, and the feasibility of the approach was established.
Summary/Accomplishments (Outputs/Outcomes):Based on the requirements for the new membrane, two potential membrane materials were selected for evaluation. Composite membranes prepared from the candidate materials were evaluated in permeation tests with gas mixtures containing two amines commonly used as catalysts in foundry cold box operations. Data obtained with both triethylamine/nitrogen and dimethylethylamine/nitrogen mixtures showed that one of the two membrane types easily met the target permeability and selectivity values established for a viable process and was also stable in the presence of high concentrations of catalyst vapor.
Based on the experimental data obtained with the selected membrane, the performance of a cold box exhaust gas treatment system using the newly developed membrane was calculated. The capital and operating cost of the selected system design was estimated. The system recovers 15 kg/h of excess catalyst (in this case triethylamine). We expect to be able to standardize the system design, with only the capacity varying, so that engineering design costs are spread over several systems and other economies of scale achieved. On this basis, the cost of a 250-scfm treatment system is estimated to be $230,000. This unit recovers 15 kg/h of water-free amine that can be blended directly with fresh catalyst for full credit. Operated on a continuous basis, this unit would recover 126,000 kg/year of triethylamine with a value of $376,000, leading to a payback time due to the value of the recovered amine of less than one year. No credit is taken for the avoided cost of treating the catalyst vapor emissions.
Conclusions:The experimental work and the technical and economic analysis demonstrated the feasibility of a membrane process to recover valuable catalyst vapors from cold box core exhaust streams for reuse in the cold box. In favorable cases, the cost of the process is completely covered by the value of the recovered catalyst vapors. System payback times of less than one year may be achieved. If these economics can be demonstrated in the field, the technology would be widely adopted by the foundry industry, eliminating a serious pollution source as well as achieving significant cost savings.
Initial users are likely to be foundries that operate on a continuous basis, at which significant amounts of catalyst could be recovered from a single machine. There are about 300 such foundries in the United States and more overseas. The potential U.S. market is $50 million in these larger plants, with an industry-wide market of $100-200 million.
This project focused on recovery and reuse of catalyst vapors from foundry cold box core machines. However, the process could be more widely applied to other operations that produce flammable solvent vapors. Examples include drying ovens in the printing and surface finishing industries or spray drying procedures in the food or pharmaceutical industries.