# US 10,871,167 B2 · Reduced emission gas seal > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,871,167 B2 - Document ID: US10871167B2 - Status: Granted - Kind: B2 - Application number: 16/356,433 - Filed: 2019-03-18 - Published: 2019-07-11 - Granted: 2020-12-22 - Earliest claimed: 2016-06-10 - Assignees: John Crane UK Limited - Applicants: John Crane UK Ltd. - Inventors: Ian Martyn Goldswain; Kanza Amanullah; Raphael Rouillon - Web page: https://patentgrep.com/patent/US10871167B2 ## CPC - F04D 29/124: {with special means for adducting cooling or sealing fluid} - F04D 29/122: {especially adapted for elastic fluid pumps} - F16J 15/3404: {and characterised by parts or details relating to lubrication, cooling or venting of the seal} - F16J 15/3412: {with cavities (F16J15/3424 takes precedence)} - F16J 15/342: {with means for feeding fluid directly to the face} - F16J 15/3484: {Tandem seals} - F16J 15/40: by means of fluid - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS ## Abstract A dry gas mechanical seal system configured to inhibit the emission of process gas. The mechanical seal system having tandem first and second stage seals, and a single separation gas supply subsystem configured to direct a supply of separation gas from an inlet through interfacing portions of the first stage seal into a process cavity and from the inlet through the interfacing portions of the second stage seal and out through an outlet to the atmosphere, thereby inhibiting the emission of process gas between a compressor housing and a rotating compressor shaft. ## Claims ### Claim 1 A mechanical seal system for a compressor operating on a process gas in a process cavity at a process cavity pressure, the mechanical seal system comprising: a mechanical seal including a rotating ring operably coupled to a compressor shaft, and a stationary ring operably biased towards the rotating ring by a biasing mechanism operably, coupled to a compressor housing, the rotating ring defining grooves that during normal operation are configured to pressurize gas passing between interfacing portions of the rotating ring and the stationary ring to partially counteract a biasing force of the biasing mechanism; a dense barrier gas supply subsystem configured to direct a supply of dense barrier gas from an inlet through the interfacing portions of the rotating ring and the stationary ring at a pressure below the process cavity pressure, during normal operation the grooves of the mechanical seal configured to pressurize the dense barrier gas to a pressure above the process cavity pressure to promote an upstream flow of the dense barrier gas from an inner diameter of the mechanical seal to an outer diameter of the mechanical seal and into the process cavity and to maintain an interface gap between the interfacing portions of the rotating ring and the stationary ring; and a starting mechanism configured to supply an additional supply gas into the interfacing portions of the rotating ring and the stationary ring during a starting operation to provide an initial gap between the interfacing portions until the rotating ring reaches a rotational speed at which the interface gap between the interfacing portions is sustainable. ### Claim 2 (depends on 1) The mechanical seal system of claim 1, wherein the starting mechanism includes a pressure balance line, separate from the inlet of the dense barrier gas supply subsystem, configured to enable a flow of process gas into the interfacing portions of the rotating ring and the stationary ring during the starting operation. ### Claim 3 (depends on 2) The mechanical seal system of claim 2, wherein the pressure balance line is closed after the starting operation. ### Claim 4 (depends on 1) The mechanical seal system of claim 1, wherein the starting mechanism includes an actuator configured to create a mechanical separation between the interfacing portions of the rotating ring and the stationary ring during the starting operation, thereby artificially providing the initial gap between the interfacing portions until the rotating ring reaches a rotational speed at which the interface gap between the interfacing portions is sustainable. ### Claim 5 (depends on 1) The mechanical seal system of claim 1, wherein the inlet of the dense barrier gas supply subsystem is at least partially closed during the starting operation. ### Claim 6 (depends on 1) The mechanical seal system of claim 1, wherein the dense barrier gas supply subsystem includes a harrier gas outlet configured to enable the dense barrier gas to be one of vented to the atmosphere, recycled back into the dense barrier gas supply subsystem, mixed with fuel powering the compressor, and a combination thereof. ### Claim 7 (depends on 6) The mechanical seal system of claim 6, wherein the outlet is at least partially closed during the starting operation. ### Claim 8 (depends on 1) The mechanical seal system of claim 1, wherein the dense barrier gas is one of nitrogen, carbon dioxide, air, and a combination thereof. ### Claim 9 (depends on 1) The mechanical seal system of claim 1, further comprising a second stage seal including a rotating ring and a stationary ring. ### Claim 10 (depends on 1) The mechanical seal system of claim 1, wherein the mechanical seal system is a tandem, non-contacting dry gas sealing system. ### Claim 11 A non-contacting, dry gas, tandem mechanical seal system having a starting mechanism configured to artificially provide an initial gap between interfacing portions of a first stage seal during a starting operation, the mechanical seal system comprising: a first stage seal including a rotating ring operably coupled to a compressor shaft, and a stationary ring operably biased towards the rotating ring and operably coupled to a compressor housing, the rotating ring defining grooves that during normal operation are configured to pressurize gas passing between interfacing portions of the rotating ring and the stationary ring; a dense barrier gas supply subsystem configured to direct a supply of dense barrier gas through the interfacing portions of the rotating ring and the stationary ring at a pressure below a process cavity pressure of a process cavity, during normal operation the grooves of the first stage seal configured to pressurize the dense barrier gas to a pressure above the process cavity pressure to promote an upstream flow of the dense barrier gas from an inner diameter of the first stage seat to an outer diameter of the first stage seat and into the process cavity and to maintain an interface gap between the interfacing portions of the rotating ring and the stationary ring; and a starting mechanism configured to supply an additional supply of gas into the interfacing portions of the rotating ring and the stationary ring during a starting operation to artificially provide an initial gap between the interfacing portions until the rotating ring reaches a rotational speed at which the interface gap between the interfacing portions is sustainable. ### Claim 12 (depends on 11) The mechanical seal system of claim 11, wherein the starting mechanism includes a pressure balance line configured to enable a flow of process gas into the interfacing portions of the rotating ring and the stationary ring during the starting operation. ### Claim 13 (depends on 12) The mechanical seal system of claim 12, wherein the pressure balance line is closed after the starting operation. ### Claim 14 (depends on 11) The mechanical seal system of claim 11, wherein the starting mechanism includes an actuator configured to create a mechanical separation between the interfacing portions of the rotating ring and the stationary ring during the starting operation. ### Claim 15 (depends on 11) The mechanical seal system of claim 11, wherein the dense barrier gas supply subsystem includes a single inlet. ### Claim 16 (depends on 15) The mechanical seal system of claim 15, wherein the inlet is at least partially closed during the starting operation. ### Claim 17 (depends on 11) The mechanical seal system of claim 11, wherein the dense barrier gas supply subsystem includes a barrier gas outlet configured to enable the dense barrier gas to be one of vented to the atmosphere, recycled hack into the dense harder gas supply subsystem, mixed with fuel powering the compressor, and a combination thereof. ### Claim 18 (depends on 17) The mechanical seal system of claim 17, wherein the outlet is at least partially closed during the starting operation. ### Claim 19 (depends on 11) The mechanical seal system of claim 11, wherein the dense barrier gas is one of nitrogen, carbon dioxide, air, and a combination thereof. ### Claim 20 A method of artificially providing, an initial gap between interfacing portions of a mechanical seal during a starting operation, the method comprising: providing a direct supply of dense barrier gas through interfacing portions of a rotating ring and a stationary ring of mechanical seal at a pressure below a process cavity pressure, wherein during normal operation grooves defined by the mechanical seal are configured to pressurize the dense barrier gas to a pressure above the process cavity pressure of a process cavity to promote an upstream flow of the dense barrier gas from an inner diameter of the mechanical seal to an outer diameter of the mechanical seal and into the process cavity to maintain an interface gap between the interfacing portions of the rotating ring and the stationary ring; and providing an additional supply of gas into the interfacing portions of the rotating ring and the stationary ring during the starting operation to artificially provide the initial gap between the interfacing portions until the rotating ring reaches a rotational speed at which the interface gap between the interfacing portions is sustainable. ### Claim 21 A mechanical seal system for a compressor operating on a process gas in a process cavity at a process cavity pressure, the mechanical seal system comprising: a mechanical seal including a rotating ring operably coupled to a compressor shaft, and a stationary ring operably biased towards the rotating ring by a biasing mechanism operably coupled to a compressor housing, the rotating ring defining grooves that during normal operation are configured to pressurize gas passing between interfacing portions of the rotating ring and the stationary ring to partially counteract a biasing force of the biasing mechanism; a dense barrier gas supply subsystem configured to direct a supply of dense barrier gas from an inlet through the interfacing portions of the rotating ring and the stationary ring at a pressure below the process cavity pressure, during normal operation the grooves of the mechanical seal configured to pressurize the dense barrier gas to a pressure above the process cavity pressure to promote an upstream flow of the dense barrier gas from an inner diameter of the mechanical seal to an outer diameter of the mechanical seal and into the process cavity and to maintain an interface gap between the interfacing portions of the rotating ring and the stationary, ring; and a starting mechanism configured to supply the process gas from inside the compressor into the interfacing portions of the rotating ring and the stationary ring during a starting operation to provide an initial gap between the interfacing portions until the rotating ring reaches a rotational speed at which the interface gap between the interfacing portions is sustainable. ### Claim 22 (depends on 21) The mechanical seal system of claim 21, wherein the starting mechanism includes a balance pressure line configured to enable the process gas to flow from inside the compressor into the interfacing portions of the rotating ring and the stationary ring during the starting operation. ### Claim 23 (depends on 22) The mechanical seal system of claim 22, wherein the pressure balance line is closed after the starting operation. ### Claim 24 (depends on 22) The mechanical seal system of claim 22, wherein the seal system is mounted around the compressor shaft and the pressure balance line is fluidly connected to the process cavity of the compressor. ### Claim 25 (depends on 21) The mechanical seal system of claim 21, wherein the dense barrier gas supply subsystem includes a single inlet. ### Claim 26 (depends on 25) The mechanical seal system of claim 25, wherein the inlet is at least partially closed during the starting operation. ### Claim 27 (depends on 21) The mechanical seal system of claim 21, wherein the dense barrier gas supply subsystem includes a harrier gas outlet configured to enable the dense barrier gas to be one of vented to the atmosphere, recycled back into the dense barrier gas supply subsystem, mixed with fuel powering the compressor, and a combination thereof. ### Claim 28 (depends on 27) The mechanical seal system of claim 27, wherein the outlet is at least partially closed during the starting operation. ### Claim 29 (depends on 21) The mechanical seal system of claim 21, wherein the dense barrier gas is one of nitrogen, carbon dioxide, air, and a combination thereof. ### Claim 30 A method of operating a mechanical seal operation, the method comprising: providing a direct supply of dense harrier gas to a harrier gas chamber in the seal and through interfacing portions of a rotating ring and a stationary ring of the mechanical seal at a pressure below a process cavity pressure of a process cavity, wherein during normal operation grooves defined by the mechanical seal are configured to pressurize the dense harrier gas to a pressure above the process cavity pressure to promote an upstream flow of the dense barrier gas from an inner diameter of the mechanical seal to an outer diameter of the mechanical seal and into the process cavity to maintain an interface gap between the interfacing portions of the rotating ring and the stationary ring; reducing an amount of the dense barrier gas supplied to the harrier gas chamber; providing an additional supply of process gas into the interfacing portions of the rotating ring and the stationary ring to provide the interface gap between the interfacing portions when the rotating ring is below a rotational speed at which the interface gap between the interfacing portions is sustainable.