The Basco^® type HT/AHT small shell and tube heat exchanger is designed in a highly standard way, ensuring the maximum flexibility at the lowest cost and high corrosion resistance. The number of tubes is increased under the given diameter condition, which improves the heat exchange efficiency. The dome shell nozzle design is adopted, which reduces the fluid inlet velocity, pressure drop and energy loss, thereby prolonging the equipment service life and meeting the diversified industrial application requirements.