Abstract: The invention relates to a process for controlling at least two production units whose outputs are connected in parallel in order to produce a common output flow which is intended to feed a consumer plant. It controls the common output flow as a function of a predetermined target value (u) and includes the steps consisting in measuring at least one variable representing the common output flow; for each unit, determining a control instruction corresponding to one operating state of the unit among a finite set of predetermined operating states; and controlling the units with the control instructions determined. Two variables representing the common output flow are measured and the control instructions are determined by a fuzzy-logic controller. Application to controlling a set of compressors.

Abstract: The plant for producing a product stream includes, mounted in series, several modules adapted to perform successive and distinct elementary treatments. At least two elementary treatment modules each include at least two treatment apparatuses mounted in parallel. The plant furthermore includes a device for controlling the various treatment apparatuses as a function of the product stream desired at the outlet of the plant. The control device includes sensors for measuring at least two variables representative of the product stream, and a fuzzy logic regulator adapted for controlling, in at least two distinct treatment modules, at least two treatment apparatuses of the same module, on the basis of the same measured representative variable.

Abstract: The plant comprises, on site, a compressed-air provision and distribution system (L.sub.A) with at least one dedicated air compressor (CO2, CO3), an air-gas production and provision system (L.sub.G) comprising an air treatment unit (S), with a reservoir R of the said air gas and normally fed by a compressor (CO1). In temporary operating mode, with one air compressor (CO2) off-line, the compressed air from the compressor (CO1) of the air gas provision system (S) is at least in part diverted (C), typically with pressure reduction (D), to sustain the production of the compressed air system (L.sub.A), the air gas then being at least in part provided by the reservoir (R).

Abstract: The invention is exclusively concerned with heat treatments before hardening, of metallic pieces, by cementation, carbonitridation and heating. The process concerns the feeding of a non muffle heat treatment furnace with various components including nitrogen which is produced by an adsorption or selective permeation generator and which has a residual oxygen content of the order of 2%. According to the invention, after the furnace has ceased to be in operation for a substantial period of time, it is reconditioned by injecting purer nitrogen which has a residual oxygen content lower than 0.3% and which is produced by said generator, adjusted at a lower extraction rate.

Abstract: The plant comprises, on site, a compressed-air provision and distribution system (LA) with at least one dedicated air compressor (CO2, CO3), an air-gas production and provision system (LG) comprising an air treatment unit (S), with a reservoir R of the said air gas and normally fed by a compressor (CO1). In temporary operating mode, with one air compressor (CO2) off-line, the compressed air from the compressor (CO1) of the air gas provision system (S) is at least in part diverted (C), typically with pressure reduction (D), to sustain the production of the compressed air system (LA), the air gas then being at least in part provided by the reservoir (R).