Device for the desulphurisation of petroleum, comprising a) a desulphurisation plant for petroleum containing shear metals, which, in addition to the desulphurised petroleum, forms an acid gas containing hydrogen sulphide, b) a plant for the recovery of elemental sulphur and a hydrogen sulphide containing tail gas as waste gas from acid gas of the desulphurisation plant, c) a device for producing electricity and gypsum from tail gas or from acid gas or from a mixture of acid gas and tail gas, comprising c1) a power generating device comprising a combustion device for the combustion of tail gas or acid gas or a mixture of tail gas and acid gas, wherein the energy released during the combustion is at least partially used for electricity generation, c2) a flue gas desulphurisation plant for desulphurising the combustion flue gases containing sulphur oxides which are produced during combustion, with the formation of gypsum, d) a gas pipe system for supplying acid gas from the desulphurisation plant to the elemental sulphur recovery plant and to the electricity and gypsum generating device and for supplying tail gas from the elemental sulphur recovery plant to the electricity and gypsum generating device, d1) wherein the gas pipe system comprises a gas distribution unit which in a first position supplies acid gas exclusively to the elemental sulphur recovery plant, in a second position supplies acid gas exclusively to the electricity and gypsum generating device, and, in a distribution position, supplying a first portion of the acid gas to the elemental sulphur recovery plant and a second portion of the acid gas to the electricity and gypsum generating device, characterised by e) a measuring device for determining the composition and/or calorific value of the gas before combustion in the combustion device, f) an evaluation device for comparing the determined composition with a predetermined composition or a predetermined composition range and/or for comparing the determined calorific value with a predetermined calorific value or a predetermined calorific value range, and g1) a control device and a feed device for natural gas, wherein the control device determines, in the event of a deviation from the predetermined composition or composition range and/or from the predetermined calorific value or the predetermined calorific value range determined by the evaluation device, an additional proportion of natural gas required for correction and admixes it to the gas via the feed device before combustion, and/or g2) a control means, wherein the control means adjusts the mixing ratio between the tail gas and the second part of the acid gas for correction. a) a desulphurisation plant for petroleum containing shear metals, which, in addition to the desulphurised petroleum, forms an acid gas containing hydrogen sulphide, b) a plant for the recovery of elemental sulphur and a hydrogen sulphide containing tail gas as waste gas from acid gas of the desulphurisation plant, c) a device for producing electricity and gypsum from tail gas or from acid gas or from a mixture of acid gas and tail gas, comprising c1) a power generating device comprising a combustion device for the combustion of tail gas or acid gas or a mixture of tail gas and acid gas, wherein the energy released during the combustion is at least partially used for electricity generation, c2) a flue gas desulphurisation plant for desulphurising the combustion flue gases containing sulphur oxides which are produced during combustion, with the formation of gypsum, d) a gas pipe system for supplying acid gas from the desulphurisation plant to the elemental sulphur recovery plant and to the electricity and gypsum generating device and for supplying tail gas from the elemental sulphur recovery plant to the electricity and gypsum generating device, d1) wherein the gas pipe system comprises a gas distribution unit which in a first position supplies acid gas exclusively to the elemental sulphur recovery plant, in a second position supplies acid gas exclusively to the electricity and gypsum generating device, and, in a distribution position, supplying a first portion of the acid gas to the elemental sulphur recovery plant and a second portion of the acid gas to the electricity and gypsum generating device, characterised by e) a measuring device for determining the composition and/or calorific value of the gas before combustion in the combustion device, f) an evaluation device for comparing the determined composition with a predetermined composition or a predetermined composition range and/or for comparing the determined calorific value with a predetermined calorific value or a predetermined calorific value range, and g1) a control device and a feed device for natural gas, wherein the control device determines, in the event of a deviation from the predetermined composition or composition range and/or from the predetermined calorific value or the predetermined calorific value range determined by the evaluation device, an additional proportion of natural gas required for correction and admixes it to the gas via the feed device before combustion, and/or g2) a control means, wherein the control means adjusts the mixing ratio between the tail gas and the second part of the acid gas for correction.