Plate heat exchanger and method of using

Abstract

A process for heating a cold stream with a hot stream is described. At least one of the cold inlet or outlet, the hot inlet or outlet, the cold inlet or outlet header, the hot inlet or outlet header, and the plurality of plates is made of one of two stainless steel alloys. One alloy has higher molybdenum content with copper for improved corrosion resistance and is resistant to chloride pitting, chloride SCC, and PTA SCC. The other alloy has significantly higher tensile and yield strength, which will reduce the susceptibility of the plate bundle to thermal stress damage.

What is claimed is: 
     
         1 . A process for heating a cold stream with a hot stream comprising:
 providing a plate heat exchanger comprising: a plurality of corrugated plates forming cold flow channels and hot flow channels, a cold inlet in fluid communication with the cold flow channels, a cold outlet in fluid communication with the cold flow channels, a hot inlet in fluid communication with the hot flow channels, a hot outlet in fluid communication with the hot flow channels;   introducing the cold stream to the cold inlet and the hot stream to the hot inlet and exchanging heat from the hot stream to the cold stream, the cold stream at the cold outlet having an enthalpy higher than an enthalpy of the cold stream at the cold inlet, and the hot stream at the hot outlet having an enthalpy lower than an enthalpy of the hot stream at the hot inlet;   wherein the plurality of plates is made of: a first stainless steel alloy comprising 0.005 to 0.020 wt % carbon, 9.0 to 13.0 wt % nickel, 17.0 to 19.0 wt % chromium, 0.20 to 0.50 wt % niobium, and 0.06 to 0.10 wt % nitrogen; or a second stainless steel alloy comprising 0.0005 to 0.020 wt % carbon, 10 to 30 wt % nickel, 15-24 wt % chromium, 0.20 to 0.50 wt % niobium, 0.06 to 0.10 wt % nitrogen, up to 5 wt % copper, up to 1.00 wt % silicon, up to 2.00 wt % manganese, and 0.3 to 7 wt % molybdenum.   
     
     
         2 . The process of  claim 1  wherein the first stainless steel alloy, the second stainless steel alloy, or both further comprise 0.01 to 2.0 wt % beryllium, and 0.1 to 0.5 wt % boron. 
     
     
         3 . The process of  claim 1  wherein at least one of cold inlet, the cold outlet, the hot inlet, and the hot outlet is made of the first stainless steel alloy or the second stainless steel alloy. 
     
     
         4 . The process of  claim 1  further comprising at least one of a cold inlet header in fluid communication with the cold inlet and the cold flow channels, a cold outlet header in fluid communication with the cold outlet and the cold flow channels, a hot inlet header in fluid communication with the hot inlet and the hot flow channels, a hot outlet header in fluid communication with the hot outlet and the hot flow channels, and wherein at least one of cold inlet header, the cold outlet header, the hot inlet header, and the hot outlet header is made of the first stainless steel alloy or the second stainless steel alloy. 
     
     
         5 . The process of  claim 1  wherein the plurality of plates are welded. 
     
     
         6 . The process of  claim 5  wherein the plate heat exchanger further comprises a pressure vessel containing the plurality of plates. 
     
     
         7 . The process of  claim 5  wherein the plate heat exchanger further comprises a pair of end plates clamped on the plurality of plates. 
     
     
         8 . The process of  claim 1  wherein the hot stream comprises a vapor and wherein the hot stream at least partially condenses in the plate heat exchanger. 
     
     
         9 . The process of  claim 1  wherein the cold stream comprises a liquid and wherein the cold stream at least partially vaporizes in the plate heat exchanger. 
     
     
         10 . The process of  claim 1  wherein the cold stream comprises a cooling fluid. 
     
     
         11 . The process of  claim 1  wherein the plurality of plates are welded, the plurality of plates are contained in a pressure vessel, the cold stream is a liquid mixed with a recycle gas, the hot stream is a vapor, and wherein the cold stream at least partially vaporizes in the plate heat exchanger, and the hot stream at least partially condenses in the plate heat exchanger. 
     
     
         12 . The process of  claim 1  wherein the plurality of plates are welded, the plate heat exchanger further comprises a pair of end plates clamped on the plurality of plates, the cold stream is a liquid, and the hot stream is a liquid. 
     
     
         13 . The process of  claim 1  wherein the cold inlet and the hot outlet are at one end of the plate heat exchanger and the cold outlet and the hot inlet are at the other end of the plate heat exchanger. 
     
     
         14 . The process of  claim 1  wherein the plate heat exchanger operates at a temperature above about 590° C. 
     
     
         15 . A welded plate heat exchanger comprising:
 a plurality of welded corrugated plates forming cold flow channels and hot flow channels, a cold inlet in fluid communication with the cold flow channels, a cold outlet in fluid communication with the cold flow channels, a hot inlet in fluid communication with the hot flow channels, a hot outlet in fluid communication with the hot flow channels;   wherein the plurality of plates is made of: a first stainless steel alloy comprising 0.005 to 0.020 wt % carbon, 9.0 to 13.0 wt % nickel, 17.0 to 19.0 wt % chromium, 0.20 to 0.50 wt % niobium, and 0.06 to 0.10 wt % nitrogen; or a second stainless steel alloy comprising 0.0005 to 0.020 wt % carbon, 10 to 30 wt % nickel, 15-24 wt % chromium, 0.20 to 0.50 wt % niobium, 0.06 to 0.10 wt % nitrogen, up to 5 wt % copper, up to 1.00 wt % silicon, up to 2.00 wt % manganese, 0.3 to 7 wt % molybdenum, 0.01 to 2.0 wt % beryllium, and 0.1 to 0.5 wt % boron.   
     
     
         16 . The welded plate heat exchanger of  claim 15  wherein at least one of cold inlet, the cold outlet, the hot inlet, and the hot outlet is made of the first stainless steel alloy or the second stainless steel alloy. 
     
     
         17 . The welded plate heat exchanger of  claim 15  further comprising at least one of a cold inlet header in fluid communication with the cold inlet and the cold flow channels, a cold outlet header in fluid communication with the cold outlet and the cold flow channels, a hot inlet header in fluid communication with the hot inlet and the hot flow channels, a hot outlet header in fluid communication with the hot outlet and the hot flow channels, and wherein at least one of cold inlet header, the cold outlet header, the hot inlet header, and the hot outlet header is made of the first stainless steel alloy or the second stainless steel alloy. 
     
     
         18 . The welded plate heat exchanger of  claim 15  further comprising a pressure vessel containing the plurality of plates. 
     
     
         19 . The welded plate heat exchanger of  claim 15  further comprising a pair of end plates clamped on the plurality of plates. 
     
     
         20 . The welded plate heat exchanger of  claim 15  wherein the cold inlet and the hot outlet are at one end of the plate heat exchanger and the cold outlet and the hot inlet are at the other end of the plate heat exchanger.