Heat　recovery　loop　(HRL)　is　an　indirect　approach　for　waste　Heat　Integration　between　plants.　The　mathematical　model　for　HRL　design　is　a　complex　and　nonlinear　problem,　which　results　in　a　non-convex　Mixed　Integer　Nonlinear　Programming　(MINLP)　model.　Solving　the　problem　without　any　strategy　is　difficult　since　computational　results　can　easily　be　trapped　in　the　local　optimum　solutions.　This　is　mainly　due　to　the　reasons　that　operation　cost,　capital　cost　of　heat　exchanger　networks,　piping　and　pumping　cost　are　considered　simultaneously.　To　overcome　this　limitation,　an　efficient　optimization　algorithm　is　proposed　for　the　complex　problem.　With　application　of　convex　reformulation　and　piecewise　wise　relaxation,　the　problem　can　be　reformulated　as　a　convex　MINLP　model,　in　which　the　objective　function　is　convex　and　all　constraints　are　linear.　The　computational　efforts　are　reduced　largely　and　better　solutions　can　be　obtained　for　the　HRL　design.　As　this　work　concentrates　on　low　grade　heat　recovery,　hot　water　is　selected　as　the　intermediate　fluid　to　achieve　waste　Heat　Integration　between　plants.　An　industrial　case　is　demonstrated　to　illustrate　the　effectiveness　of　the　proposed　algorithm.　(C)　2016　Elsevier　Ltd.　All　rights　reserved.