Novel fuel production plant and seawater desalination system for use therein

Abstract

A novel fuel producing section produces synthesized gas from a feedstock and synthesizes novel fuel from the synthesized gas thus produced, and has exhaust heat recovery boilers for generating steam by recovering excess heat generated from the synthesizing processes. An exhaust heat utilizing section includes steam turbines driven with the steam generated from the exhaust heat recovery boilers. An open circulation cooling water supply section supplies cooling water for a plant, including water for cooling exhausts of the steam turbines, and includes a seawater desalination system for desalinating seawater by the evaporation method and supplying desalinated water to replenish the cooling water. The cooling water supplied from the open circulation cooling water supply section is used in condensing of the desalinated water produced by the seawater desalination system.

Description

TECHNICAL FIELD [0001] The present invention relates to a novel fuel production plant for producing novel fuel, and to a seawater desalination system for use in the plant. BACKGROUND ART [0002] Recently, attention has been focused on plants for producing novel fuel, such as Gas-To-Liquid (GTL) and dimethylether (DME). As a novel fuel production plant, one known example for producing dimethylether by using natural gas as a feedstock is disclosed in, e.g., JP,A 10-195008. DISCLOSURE OF THE INVENTION [0003] In plants for producing novel fuel, such as GTL and DME, (hereinafter referred to as “novel fuel production plants” or simply as “plants”), for example, a partial oxidation method or an auto-thermal reforming method using hydrocarbons, etc. as a feedstock is employed to produce synthesized gas necessary for synthesizing fuel. In those synthesized gas producing methods, the temperature of the synthesized gas at an outlet of a reaction / reforming furnace is very high (1200-1500° C.). O...

AI Technical Summary

Benefits of technology

[0004] A system using steam turbines requires a large amount of cooling water to condense steam. Hitherto, in facilities requiring a large amount of cooling water, seawater has been used in many cases primarily for the economical reason. However, the merit resulting from using seawater as the cooling water is reduced because of regulations, such as charging for use of seawater and a limitation on the temperature difference between seawater and cooling water (i.e., the difference between the temperature of returned seawater and the temperature of supplied seawater), which have been legislated with recent increasing environmental awareness. The limitation on the temperature difference between seawater and cooling water often increases the amount of required cooling water 3-5 times that required in the past. Under such a situation, large-scaled water taking-in equipment has to be installed and the economical merit is lost in most cases. For that reason, it is tried to employ, as a cooling water system for a plant, an open circulation cooling water system provided with a cooling tower, and to minimize the amount of used seawater by compensating for only losses, which are caused due to evaporation, scattering and forced blow from the cooling tower, with desalination of seawater.

[0006] An object of the present invention is to provide a novel fuel production plant and a seawater desalination system for use therein in which an evaporation water production system can be applied at a seawater intake amount comparable to that required in a system using the reverse osmosis membrane method, the degree of freedom in selecting the plant installation site is high, salinity of produced water is reduced as compared with that in the case using the reverse osmosis membrane method, and the merit of the evaporation water production system having a low maintenance cost can be enjoyed.

[0008] With that arrangement, fresh water can be produced at a seawater intake amount comparable to that required in a system using the reverse osmosis membrane method, and the cooling water can be supplied with a lower remaining salinity in the produced water and a lower maintenance cost than those in the case using the reverse osmosis membrane method.

[0010] With that arrangement, fresh water can be produced at a seawater intake amount comparable to that required in a system using the reverse osmosis membrane method, and the cooling water can be supplied with a lower remaining salinity in the produced water and a lower maintenance cost than those in the system using the reverse osmosis membrane method.

Problems solved by technology

In the novel fuel production plant, therefore, a large amount of excess heat is inevitable generated, thus resulting in the necessity of installing exhaust heat boilers to generate high- and medium-pressure steam for heat recovery.

A system using steam turbines requires a large amount of cooling water to condense steam.

However, the merit resulting from using seawater as the cooling water is reduced because of regulations, such as charging for use of seawater and a limitation on the temperature difference between seawater and cooling water (i.e., the difference between the temperature of returned seawater and the temperature of supplied seawater), which have been legislated with recent increasing environmental awareness.

The limitation on the temperature difference between seawater and cooling water often increases the amount of required cooling water 3-5 times that required in the past.

Under such a situation, large-scaled water taking-in equipment has to be installed and the economical merit is lost in most cases.

In such a try, for the desalination of seawater, a reverse osmosis membrane method is primarily studied because this method requires a less seawater intake amount in spite of accompanying the problems that the remaining salinity is high, a plant cannot be practically installed in some cases depending on properties of seawater, and a membrane occupying about ⅓ of the overall plant cost has to be frequently replaced, thus resulting in a higher maintenance cost.

Images