Efficient algorithm for a special case of order consolidation

Processing according to the prior given orders is often confronted within industry. How to consolidate similar product orders to form as many batches as possible is one method of productive efficiency improvement. A special case is considered where the orders of only single or a specific pair of products may be grouped in a batch whose size is Q. The problem is to consolidate orders so as to maximise the number of batches. The problem is NP-complete in general. A special kind of order consolidation is considered and its efficient algorithm is devised.