I know nothing about heat exchangers. However, any major pump manufacturer should be able to quote a pump for this service. They should be familiar with this chemical and have no problems proposing a design. I would offer a few words of caution. Some material compatibility charts may indicate that carbon steel is acceptable for low temperature lean amine (MDEA). I would not agree. I would consider 316 SS (API material class A-8) as a minimum for this service. All of our lean amine pumps that were originally installed as carbon steel had to be changed out to stainless steel eventually. A pump manufacturer might quote carbon steel in order to be the low bid.
As a point of personal preference, I dislike questions that ask for a recommended manufacturer since it tends to encourage sales engineers to try and peddle their wares. It would be more appropriate to ask questions regarding pump configuration, materials of construction, NPSH considerations, etc.
Johnny Pellin