Diesel hot water boiler

we are consulted by one of our customers for the provision of:
• diesel hot water boiler, minimum capacity 350 kw. qty = 2.
• water out 85-95 degrees.
• water in temperature will vary between 20 and 65 degrees depending on the process.
• the low temperature will only be valid for the first 90 minutes of preheating.
• flow rate expected 333-256 lt/min. the max flow will only be valid for 90 minutes of preheating phase.
we would like to obtain a